Color conversion sheet, light source unit comprising same, display and lighting device

ABSTRACT

A color conversion sheet that converts incident light into light with a wavelength longer than that of the incident light, the color conversion sheet including the following layer (A) and layer (B): the layer (A): a layer containing an organic light-emitting material (a) that exhibits light emission with a peak wavelength observed in a region of 500 nm or more and 580 nm or less by using excitation light in a wavelength range of 400 nm or more and 500 nm or less, and a binder resin; and the layer (B): a layer containing an organic light-emitting material (b) that exhibits light emission with a peak wavelength observed in a region of 580 nm or more and 750 nm or less by being excited by either or both of excitation light in a wavelength range of 400 nm or more and 500 nm or less and light emission from the organic light-emitting material (a), and a binder resin; wherein SP A &gt;SP B  where SP values as solubility parameters of the binder resin contained in the layer (A) and the binder resin contained in the layer (B) are SP A  (cal/cm 3 ) 0.5  and SP B  (cal/cm 3 ) 0.5 , respectively.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Phase application of PCT/JP2018/018890, filedMay 16, 2018, which claims priority to Japanese Patent Application No.2017-109739, filed Jun. 2, 2017, the disclosures of these applicationsbeing incorporated herein by reference in their entireties for allpurposes.

FIELD OF THE INVENTION

The present invention relates to a color conversion sheet, a lightsource unit including the same, a display and a lighting apparatus.

BACKGROUND OF THE INVENTION

Application of a multicoloring technique by a color conversion method toliquid crystal displays, organic electroluminescence (EL) displays,lighting apparatuses, and the like is being energetically studied. Colorconversion means converting light emission from a light-emitting bodyinto light with a longer wavelength and means converting blue lightemission into green or red light emission, for example.

A composition having this color conversion function (hereinafter,referred to as “a color conversion composition”) is formed into a sheetform and is combined with a blue light source, for example, whereby thethree primary colors of blue, green, and red can be obtained, that is,white light can be obtained from the blue light source. A white lightsource obtained by combining the blue light source and the sheet havingthe color conversion function (hereinafter, referred to as “a colorconversion sheet”) with each other forms a backlight unit, and thisbacklight unit, a liquid crystal drive part, and color filters arecombined with each other, whereby a full-color display can be produced.Without the liquid crystal drive part, the residual part can be used asa white light source as it is, which can be used as the white lightsource such as LED lighting.

Improvement in color reproducibility is a problem in liquid crystaldisplays using the color conversion method. Narrowing the full width athalf maximum of the respective emission spectra of blue, green, and redof the backlight unit to increase the color purity of each of blue,green, and red is effective in improving color reproducibility.

To solve this problem, developed is a technique that uses quantum dotsformed of inorganic semiconductor fine particles as a component of thecolor conversion composition (refer to Patent Literature 1, forexample). Although the technique using the quantum dots is indeed narrowin the full width at half maximum of green and red emission spectra toimprove color reproducibility, the quantum dots are vulnerable to heatand water and oxygen in the air and are thus deficient in durability onthe other hand. In addition, there is a problem in that cadmium iscontained, for example.

Also developed is a technique that uses a light-emitting material formedof an organic substance as a component of the color conversioncomposition in place of the quantum dots. Disclosed as examples of thetechnique that uses an organic light-emitting material as the componentof the color conversion composition are one that uses a coumarinderivative (refer to Patent Literature 2, for example), one that uses arhodamine derivative (refer to Patent Literature 3, for example), andone that uses a pyrromethene derivative (refer to Patent Literature 4,for example).

PATENT LITERATURE

-   Patent Literature 1: Japanese Patent Application Laid-open No.    2012-22028-   Patent Literature 2: Japanese Patent Application Laid-open No.    2007-273440-   Patent Literature 3: Japanese Patent Application Laid-open No.    2001-164245-   Patent Literature 4: Japanese Patent Application Laid-open No.    2011-241160

SUMMARY OF THE INVENTION

However, the technique using these organic light-emitting materials isinsufficient in achieving an improvement in both color reproducibilityand luminance. In particular, deficient is a technique that achieves awide color gamut and improves luminance sufficiently, using organiclight-emitting materials exhibiting light emission with high colorpurity.

A problem to be solved by the present invention is to provide a colorconversion sheet for use in displays, lighting apparatuses, and thelike, the color conversion sheet being able to achieve both high colorreproducibility and high luminance.

To solve the problem described above and to achieve the object, a colorconversion sheet according to the present invention converts incidentlight into light with a wavelength longer than that of the incidentlight, and includes the following layer (A) and layer (B):

the layer (A): a layer containing an organic light-emitting material (a)that exhibits light emission with a peak wavelength observed in a regionof 500 nm or more and 580 nm or less by using excitation light in awavelength range of 400 nm or more and 500 nm or less, and a binderresin; and

the layer (B): a layer containing an organic light-emitting material (b)that exhibits light emission with a peak wavelength observed in a regionof 580 nm or more and 750 nm or less by being excited by either or bothof excitation light in a wavelength range of 400 nm or more and 500 nmor less and light emission from the organic light-emitting material (a),and a binder resin;

wherein SP_(A)>SP_(B) where SP values as solubility parameters of thebinder resin contained in the layer (A) and the binder resin containedin the layer (B) are SP_(A)(cal/cm³)^(0.5) and SP_(B) (cal/cm³)^(0.5),respectively.

In the color conversion sheet according to the present invention, thepeak wavelength of the light emission of the organic light-emittingmaterial (a) is 500 nm or more and 550 nm or less, and the peakwavelength of the light emission of the organic light-emitting material(b) is 580 nm or more and 680 nm or less.

In the color conversion sheet according to the present invention,SP_(B)≤10.0 where an SP value as a solubility parameter of the binderresin contained in the layer (B) is SP_(B) (cal/cm³)^(0.5).

In the color conversion sheet according to the present invention,9.0≤SP_(B)≤10.0 where an SP value as a solubility parameter of thebinder resin contained in the layer (B) is SP_(B) (cal/cm³)^(0.5).

In the color conversion sheet according to the present invention, thebinder resin contained in the layer (B) is an acrylic resin.

In the color conversion sheet according to the present invention, thebinder resin contained in the layer (A) is a polyester resin.

In the color conversion sheet according to the present invention, acontent w_(a) of the organic light-emitting material (a) in the layer(A) and a content w_(b) of the organic light-emitting material (b) inthe layer (B) have a relation of w_(a)≥w_(b).

In the color conversion sheet according to the present invention, atleast one of the organic light-emitting material (a) and the organiclight-emitting material (b) is a compound represented by General Formula(1):

(where X is C—R⁷ or N; R¹ to R⁹ are the same as or different from eachother and are selected from hydrogen, an alkyl group, a cycloalkylgroup, a heterocyclic group, an alkenyl group, a cycloalkenyl group, analkynyl group, a hydroxy group, a thiol group, an alkoxy group, analkylthio group, an aryl ether group, an aryl thioether group, an arylgroup, a heteroaryl group, halogen, a cyano group, an aldehyde group, acarbonyl group, a carboxy group, an oxycarbonyl group, a carbamoylgroup, an amino group, a nitro group, a silyl group, a siloxanyl group,a boryl group, a phosphine oxide group, and a condensed ring and analiphatic ring formed between adjacent substituents).

In the color conversion sheet according to the present invention, boththe organic light-emitting material (a) and the organic light-emittingmaterial (b) are each a compound represented by General Formula (1).

In the color conversion sheet according to the present invention, thelayer (A) further contains an organic light-emitting material (c) thatexhibits light emission with a peak wavelength observed in a region of580 nm or more and 750 nm or less by being excited by either or both ofexcitation light in a wavelength range of 400 nm or more and 500 nm orless and light emission from the organic light-emitting material (a).

In the color conversion sheet according to the present invention, acontent w_(a) of the organic light-emitting material (a) in the layer(A) and a content w_(c) of the organic light-emitting material (c) inthe layer (A) have a relation of w_(a)≥w_(c).

In the color conversion sheet according to the present invention, theorganic light-emitting material (c) is a compound represented by GeneralFormula (1):

(where X is C—R⁷ or N; R¹ to R⁹ are the same as or different from eachother and are selected from hydrogen, an alkyl group, a cycloalkylgroup, a heterocyclic group, an alkenyl group, a cycloalkenyl group, analkynyl group, a hydroxy group, a thiol group, an alkoxy group, analkylthio group, an aryl ether group, an aryl thioether group, an arylgroup, a heteroaryl group, halogen, a cyano group, an aldehyde group, acarbonyl group, a carboxy group, an oxycarbonyl group, a carbamoylgroup, an amino group, a nitro group, a silyl group, a siloxanyl group,a boryl group, a phosphine oxide group, and a condensed ring and analiphatic ring formed between adjacent substituents).

In the color conversion sheet according to the present invention, thelayer (B) further contains an organic light-emitting material (d) thatexhibits light emission with a peak wavelength observed in a region of500 nm or more and 580 nm or less by using excitation light in awavelength range of 400 nm or more and 500 nm or less.

In the color conversion sheet according to the present invention, theorganic light-emitting material (d) is a compound represented by GeneralFormula (1):

(where X is C—R⁷ or N; R¹ to R⁹ are the same as or different from eachother and are selected from hydrogen, an alkyl group, a cycloalkylgroup, a heterocyclic group, an alkenyl group, a cycloalkenyl group, analkynyl group, a hydroxy group, a thiol group, an alkoxy group, analkylthio group, an aryl ether group, an aryl thioether group, an arylgroup, a heteroaryl group, halogen, a cyano group, an aldehyde group, acarbonyl group, a carboxy group, an oxycarbonyl group, a carbamoylgroup, an amino group, a nitro group, a silyl group, a siloxanyl group,a boryl group, a phosphine oxide group, and a condensed ring and analiphatic ring formed between adjacent substituents).

In the color conversion sheet according to the present invention, inGeneral Formula (1), X is C—R⁷ and R⁷ is a group represented by GeneralFormula (2):

(where r is selected from the group consisting of hydrogen, an alkylgroup, a cycloalkyl group, a heterocyclic group, an alkenyl group, acycloalkenyl group, an alkynyl group, a hydroxy group, a thiol group, analkoxy group, an alkylthio group, an aryl ether group, an aryl thioethergroup, an aryl group, a heteroaryl group, halogen, a cyano group, analdehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group,a carbamoyl group, an amino group, a nitro group, a silyl group, asiloxanyl group, a boryl group, and a phosphine oxide group; k is aninteger of 1 to 3; when k is 2 or more, rs are the same as or differentfrom each other).

In the color conversion sheet according to the present invention, inGeneral Formula (1), R¹, R³, R⁴, and R⁶ are the same as or differentfrom each other and are substituted or unsubstituted phenyl groups.

In the color conversion sheet according to the present invention, inGeneral Formula (1), R¹, R³, R⁴, and R⁶ are the same as or differentfrom each other and are substituted or unsubstituted alkyl groups.

The color conversion sheet according to the present invention furtherincludes a light extraction layer between the layer (A) and the layer(B).

A light source unit according to the present invention includes: a lightsource; and the color conversion sheet according to any one of theabove-mentioned inventions.

In the light source unit according to the present invention, anarrangement of the light source and the following layer (A) and layer(B) included in the color conversion sheet is an arrangement of thelight source, the layer (A), and the layer (B) in this order:

the layer (A): a layer containing the organic light-emitting material(a) that exhibits light emission with a peak wavelength observed in aregion of 500 nm or more and 580 nm or less by using excitation light ina wavelength range of 400 nm or more and 500 nm or less, and a binderresin; and

the layer (B): a layer containing the organic light-emitting material(b) that exhibits light emission with a peak wavelength observed in aregion of 580 nm or more and 750 nm or less by being excited by eitheror both of excitation light in a wavelength range of 400 nm or more and500 nm or less and light emission from the organic light-emittingmaterial (a), and a binder resin.

In the light source unit according to the present invention, the lightsource is a light-emitting diode having maximum emission in a wavelengthrange of 400 nm or more and 500 nm or less.

A display according to the present invention includes the light sourceunit according to any one of the above-mentioned inventions.

A display according to the present invention has a screen size of 20inches or less.

A display according to the present invention has a color gamut coverageof 96% or more in the (u′,v′) color space with respect to the DCI-P3color gamut standard.

A lighting apparatus according to the present invention includes thelight source unit according to any one of the above-mentionedinventions.

The color conversion sheet according to the present invention producesan effect of making it possible to achieve both high colorreproducibility and high luminance. The light source unit, the display,and the lighting apparatus according to the present invention includesuch a color conversion sheet and thus produce an effect of making itpossible to achieve both high color reproducibility and high luminance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of an example of a color conversionsheet according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of another example of the colorconversion sheet according to the embodiment of the present invention.

FIG. 3 is a schematic sectional view of an example in which a lightextraction layer is included in the color conversion sheet according tothe embodiment of the present invention.

FIG. 4 is a schematic sectional view of an example in which barrierlayers are included in the color conversion sheet according to theembodiment of the present invention.

FIG. 5 is a schematic sectional view of another example in which thebarrier layers are included in the color conversion sheet according tothe embodiment of the present invention.

FIG. 6 is a diagram exemplifying an absorption spectrum of a compound ofSynthesis Example 1 in the Examples of the present invention.

FIG. 7 is a diagram exemplifying an emission spectrum of the compound ofSynthesis Example 1 in the Examples of the present invention.

FIG. 8 is a diagram exemplifying an absorption spectrum of a compound ofSynthesis Example 2 in the Example of the present invention.

FIG. 9 is a diagram exemplifying an emission spectrum of the compound ofSynthesis Example 2 in the Example of the present invention.

FIG. 10 is a diagram exemplifying an emission spectrum of a colorconversion sheet in Example 1 of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The following specifically describes preferred embodiments of a colorconversion sheet, a light source unit including the same, a display, anda lighting apparatus according to the present invention. It should benoted that the present invention is not limited to the followingembodiments and can be embodied in a variously modified manner inaccordance with objects and uses.

<Color Conversion Sheet>

The color conversion sheet according to the embodiment of the presentinvention is a color conversion sheet that converts incident light froma light-emitting body such as a light source into light with awavelength longer than that of the incident light and includes thefollowing layer (A) and layer (B). The layer (A) is a layer containingan organic light-emitting material (a) and a binder resin. The organiclight-emitting material (a) is a light-emitting material formed of anorganic substance that exhibits light emission with a peak wavelengthobserved in a region of 500 nm or more and 580 nm or less by usingexcitation light in a wavelength range of 400 nm or more and 500 nm orless. The layer (B) is a layer containing an organic light-emittingmaterial (b) and a binder resin. The organic light-emitting material (b)is a light-emitting material formed of an organic substance thatexhibits light emission with a peak wavelength observed in a region of580 nm or more and 750 nm or less by being excited by either or both ofexcitation light in a wavelength region of 400 nm or more and 500 nm orless and light emission from the organic light-emitting material (a).

The peak wavelength of the light emission of an organic light-emittingmaterial (the organic light-emitting material (a) and the organiclight-emitting material (b), for example) can be determined by thefluorescence spectral measurement of its solution. A solvent for use inthis fluorescence spectral measurement is not limited to a particularsolvent; a solvent such as toluene, dichloromethane, or tetrahydrofurancan be suitably used. Toluene is more preferably used as this solvent solong as there is no problem about the solubility of the organiclight-emitting material.

In the following, the light emission with a peak wavelength observed inthe region of 500 nm or more and 580 nm or less is referred to as “greenlight emission.” The light emission with a peak wavelength observed inthe region of 580 nm or more and 750 nm or less is referred to as “redlight emission.”

In general, the excitation light having larger energy is more likely tocause the decomposition of a material. However, the excitation light ina wavelength range of 400 nm or more and 500 nm or less is relativelysmall in excitation energy. For this reason, the decomposition of thelight-emitting material in the color conversion composition is notcaused, and light emission with favorable color purity can be obtained.

Part of the excitation light in a wavelength range of 400 nm or more and500 nm or less partially passes through the color conversion sheetaccording to the embodiment of the present invention, and it itself canbe used as blue light emission. The color conversion sheet according tothe embodiment of the present invention contains the organiclight-emitting material (a) that exhibits the green light emission andthe organic light-emitting material (b) that exhibits the red lightemission. Consequently, when the color conversion sheet according to theembodiment of the present invention is used for a blue LED light sourcewith a sharp emission peak, sharp emission spectra are exhibited in therespective colors of blue, green, and red, and white light withfavorable color purity can be obtained. Consequently, in displays inparticular, a color gamut that has more vivid colors and is large can beefficiently made. In lighting use, light emission characteristics in thegreen region and the red region in particular are improved compared witha white LED in which a blue LED and a yellow fluorescent body arecombined with each other, which is currently in the mainstream, thusachieving a favorable white light source with improved color rendering.

To expand the color gamut to improve color reproducibility, the overlapof the emission spectra among the respective colors of blue, green, andred is preferably small.

When blue light in a wavelength range of 400 nm or more and 500 nm orless having moderate excitation energy is used as the excitation light,for example, light emission with a peak wavelength observed in a regionof 500 nm or more is used as the green light emission. In this case, theoverlap of the emission spectra between the excitation light and greenlight is small, and color reproducibility improves, which is thuspreferred. In enhancing the effect, the lower limit value of the peakwavelength of the organic light-emitting material (a) is more preferably510 nm or more, further preferably 515 nm or more, and particularlypreferably 520 nm or more.

To reduce the overlap of the emission spectra between the excitationlight and red light, light emission with a peak wavelength observed in aregion of 580 nm or less is preferably used as the green light emission.In enhancing the effect, the upper limit value of the peak wavelength ofthe organic light-emitting material (a) is more preferably 550 nm orless, further preferably 540 nm or less, and particularly preferably 535nm or less.

When light emission with a peak wavelength observed in a region of 500nm or more and 580 nm or less is used as the green light emission, lightemission with a peak wavelength observed in a region of 580 nm or moreis used as the red light emission. In this case, the overlap of theemission spectra between the green light the red light is small, andcolor reproducibility improves, which is thus preferred. In enhancingthe effect, the lower limit value of the peak wavelength of the organiclight-emitting material (b) is more preferably 610 nm or more, furtherpreferably 620 nm or more, and particularly preferably 630 nm or more.

The upper limit of the peak wavelength of the red light may be 750 nm,which is near the upper limit of the visible range, or less; when it is700 nm or less, visibility improves, which is thus more preferred. Inenhancing the effect, the upper limit value of the peak wavelength ofthe organic light-emitting material (b) is further preferably 680 nm orless and particularly preferably 660 nm or less.

That is, when the blue light in a wavelength range of 400 nm or more and500 nm or less is used as the excitation light, the peak wavelength ofthe green light is observed in a region of preferably 500 nm or more and580 nm or less, more preferably 510 nm or more and 550 nm or less,further preferably 515 nm or more and 540 nm or less, and particularlypreferably 520 nm or more and 535 nm or less. The peak wavelength of thered light is observed in a region of preferably 580 nm or more and 750nm or less, more preferably 610 nm or more and 700 nm or less, furtherpreferably 620 nm or more and 680 nm or less, and particularlypreferably 630 nm or more and 660 nm or less.

To reduce the overlap of the emission spectra to improve colorreproducibility, the full width at half maximum of the emission spectraof the respective colors of blue, green, and red are preferably small.In particular, that the full width at half maximum of the emissionspectra of the green light and the red light are small is effective inimproving color reproducibility.

The full width at half maximum of the emission spectrum of the greenlight is preferably 50 nm or less, more preferably 40 nm or less,further preferably 35 nm or less, and particularly preferably 30 nm orless, for example. The full width at half maximum of the emissionspectrum of the red light is preferably 80 nm or less, more preferably70 nm or less, further preferably 60 nm or less, and particularlypreferably 50 nm or less.

The shape of the emission spectra, which is not limited to a particularshape, preferably has a single peak because excitation energy can beefficiently used, and color purity increases. The single peak indicatesa state in which, relative to a peak having the highest intensity, thereis no peak the intensity of which is 5% or more of the highestintensity.

As described above, the color conversion sheet according to theembodiment of the present invention includes two color conversionlayers, that is, the layer (A) containing the organic light-emittingmaterial (a) and the layer (B) containing the organic light-emittingmaterial (b). The organic light-emitting material (a) and the organiclight-emitting material (b) are contained in different layers, wherebyinter-material interaction is reduced, and light emission with highercolor purity is exhibited than a case in which they are dispersed in thesame layer. The inter-material interaction between the organiclight-emitting material (a) and the organic light-emitting material (b)is reduced, whereby the organic light-emitting material (a) and theorganic light-emitting material (b) each emit light independently in therespective layers, and thus adjustment of the emission peak wavelengthand emission intensity of green and red is made easy.

That is, the color conversion sheet according to the embodiment of thepresent invention can design the optimum emission peak wavelength andemission intensity of the respective colors of blue, green, and redwithout deteriorating the characteristics of the organic light-emittingmaterial such as the organic light-emitting material (a) and the organiclight-emitting material (b) exhibiting light emission with high colorpurity. With this design, white light with good color purity can beobtained.

In the color conversion sheet according to the embodiment of the presentinvention, at least one organic light-emitting material may be containedin each of the layer (A) and the layer (B); two or more may be containedtherein. A plurality of organic light-emitting materials are mixed in atleast either the layer (A) or the layer (B), thereby enabling fineadjustment of the emission peak wavelength and emission intensity of therespective colors of blue, green, and red.

As a mixing example of a plurality of organic light-emitting materials,the layer (A) may contain an organic light-emitting material (a′) inaddition to and different from the organic light-emitting material (a),for example. The organic light-emitting material (a′) exhibits lightemission with a peak wavelength observed in a region of 500 nm or moreand 580 nm or less by using excitation light in a wavelength range of400 nm or more and 500 nm or less. The layer (B) may contain an organiclight-emitting material (b′) in addition to and different from theorganic light-emitting material (b). The organic light-emitting material(b′) exhibits light emission with a peak wavelength observed in a regionof 580 nm or more and 750 nm or less by being excited by either or bothof excitation light in a wavelength range of 400 nm or more and 500 nmor less and light emission from the organic light-emitting material (a).

The layer (A) preferably further contains an organic light-emittingmaterial (c) in addition to and different from the organiclight-emitting material (a). The organic light-emitting material (c)exhibits light emission with a peak wavelength observed in a region of580 nm or more and 750 nm or less by being excited by either or both ofexcitation light in a wavelength range of 400 nm or more and 500 nm orless and light emission from the organic light-emitting material (a).The layer (B) preferably further contains an organic light-emittingmaterial (d) in addition to and different from the organiclight-emitting material (b). The organic light-emitting material (d)exhibits light emission with a peak wavelength observed in a region of500 nm or more and 580 nm or less by using excitation light in awavelength range of 400 nm or more and 500 nm or less.

A plurality of pieces of the layer (A) and the layer (B) may be includedin the color conversion sheet according to the embodiment of the presentinvention. In this case, the compositions and forms of the layers of thepieces of the layer (A) may be the same as or different from each other.Similarly, the compositions and forms of the layers of the pieces of thelayer (B) may be the same as or different from each other.

Representative structure examples of the color conversion sheetaccording to the embodiment of the present invention include ones shownbelow. FIG. 1 is a schematic sectional view of an example of the colorconversion sheet according to the embodiment of the present invention.As illustrated in FIG. 1, this color conversion sheet 1 as an example ofthe present embodiment is a laminate of a base layer 10, the layer (A)11, and the layer (B) 12. In the structure example of this colorconversion sheet 1, a laminate of the layer (A) 11 and the layer (B) 12is laminated on the base layer 10 in order of the layer (A) 11 and thelayer (B) 12. That is, the color conversion sheet 1 includes the baselayer 10 and includes the layer (A) 11 and the layer (B) 12 with alamination structure of the layer (B)/the layer (A) on this base layer10.

FIG. 2 is a schematic sectional view of another example of the colorconversion sheet according to the embodiment of the present invention.As illustrated in FIG. 2, this color conversion sheet 1 a as anotherexample of the present embodiment is a laminate with a structure inwhich the layer (A) 11 and the layer (B) 12 are interposed between aplurality of base layers 10. In the structure example of this colorconversion sheet 1 a, a laminate of the layer (A) 11 and the layer (B)12 is laminated on one base layer 10 in order of the layer (A) 11 andthe layer (B) 12, and another base layer 10 is laminated on this layer(B) 12. That is, the color conversion sheet 1 a includes a plurality ofbase layers 10 and includes the layer (A) 11 and the layer (B) 12 with alamination structure of the layer (B)/the layer (A) in such a mannerthat they are interposed between these base layers 10.

Structure examples of the color conversion sheet according to theembodiment of the present invention include structures in which thelayer (A) 11 or the layer (B) 12 is repeated such as the layer (B)/thelayer (A)/the layer (A), the layer (B)/the layer (B)/the layer (A), andthe layer (B)/the layer (B)/the layer (A)/the layer (A), in addition tothe structure examples exemplified in FIGS. 1 and 2.

These are by way of example, and the specific structures of the colorconversion sheet according to the embodiment of the present inventionare not limited to these; structures with alterations made asappropriate by matters derived from the following description are alsoincluded in the scope of the present invention.

<Color Conversion Layer>

In the color conversion sheet according to the embodiment of the presentinvention, the color conversion layer is a layer containing a colorconversion composition or its cured object. The color conversioncomposition is a composition containing an organic light-emittingmaterial and a binder resin. The layer (A) and the layer (B) areexamples of the color conversion layer.

The thickness of the color conversion layer, which is not limited to aparticular thickness, is preferably 1 μm to 1,000 μm and more preferably10 μm to 1,000 μm. If the thickness of the color conversion layer issmaller than 1 m, the toughness of the color conversion sheetunfortunately reduces. If the thickness of the color conversion layerexceeds 1,000 μm, cracks are likely to occur, and the shaping of thecolor conversion sheet is difficult. The thickness of the colorconversion layer is more preferably 5 μm to 100 μm, further preferably10 μm to 100 μm, and particularly preferably 15 μm to 100 μm.

A film thickness (the thickness of the layer) in the present inventionrefers to a film thickness (an average film thickness) measured based onJIS K 7130 (1999) Plastics— Film and sheeting— Method A for measuringthickness by mechanical scanning in method for measuring thickness.

(Organic Light-Emitting Material)

The color conversion sheet according to the embodiment of the presentinvention contains the organic light-emitting material in the layer (A)and the layer (B). The light-emitting material in the present inventionrefers to a material that, when being irradiated with some light, emitslight with a wavelength different from that of the light. The organiclight-emitting material is a light-emitting material formed of anorganic substance.

To achieve highly efficient color conversion, the light-emittingmaterial is preferably a material that exhibits light emissioncharacteristics with high emission quantum yield. Examples of thelight-emitting material generally include known light-emitting materialssuch as inorganic fluorescent bodies, fluorescent pigments, fluorescentdyes, and quantum dots; the organic light-emitting material is preferredin view of dispersion uniformity, a reduction in the amount of use, anda reduction in environmental loads.

Examples of the organic light-emitting material include the followingones. Preferred examples of the organic light-emitting material includecompounds having a condensed aryl ring such as naphthalene, anthracene,phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene,fluoranthene, fluorene, and indene and derivatives thereof. Preferredexamples of the organic light-emitting material include compounds havinga heteroaryl ring such as furan, pyrrole, thiophene, silole,9-silafluorene, 9,9′-spirobisilafluorene, benzothiophene, benzofuran,indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline,pyridine, pyrazine, naphthyridine, quinoxaline, and pyrrolopyridine,derivatives thereof, and borane derivatives.

Preferred examples of the organic light-emitting material includestilbene derivatives such as 1,4-distyrylbenzene,4,4′-bis(2-(4-diphenylaminophenyl)ethenyl)biphenyl, and4,4′-bis(N-(stilben-4-yl)-N-phenylamino)stilbene, aromatic acetylenederivatives, tetraphenyl butadiene derivatives, aldazine derivatives,pyrromethene derivatives, and diketopyrolo[3,4-c]pyrrole derivatives.Preferred examples of the organic light-emitting material includecoumarin derivatives such as coumarin 6, coumarin 7, and coumarin 153,azole derivatives such as imidazole, thiazole, thiadiazole, carbazole,oxazole, oxadiazole, and triazole and metal complexes thereof,cyanine-based compounds such as indocyanine green, xanthene-basedcompounds such as fluorescein, eosine, and rhodamine, andthioxanthene-based compounds.

Preferred examples of the organic light-emitting material includepolyphenylene-based compounds, naphthalimide derivatives, phthalocyaninederivatives and metal complexes thereof, porphyrin derivatives and metalcomplexes thereof, oxazine-based compounds such as Nile Red and NileBlue, helicene-based compounds, and aromatic amine derivatives such asN,N′-diphenyl-N,N′-di(3-methylphenyl)-4,4′-diphenyl-1,1′-diamine.Preferred examples of the organic light-emitting material includeorganic metal complex compounds of iridium (Ir), ruthenium (Ru), rhodium(Rh), palladium (Pd), platinum (Pt), osmium (Os), rhenium (Re), and thelike. However, the organic light-emitting material of the presentinvention is not limited to these compounds described above.

The organic light-emitting material may be a fluorescent light-emittingmaterial or a phosphorescent light-emitting material; to achieve highcolor purity, a fluorescent light-emitting material is preferred. Amongthese materials, preferred are compounds having a condensed aryl ring orderivatives thereof because of high thermal stability andphotostability.

In view of solubility and the versatility of molecular structure,compounds having a coordinated bond are preferred as the organiclight-emitting material. In view of being small in full width at halfmaximum and the capability of giving highly efficient light emission,also preferred are compounds containing boron such as boron fluoridecomplexes.

Preferred examples of the organic light-emitting material (a) includecoumarin derivatives such as coumarin 6, coumarin 7, and coumarin 153;cyanine derivatives such as indocyanine green; fluorescein derivativessuch as fluorescein, fluorescein isothiocyanate, and carboxyfluoresceindiacetate; phthalocyanine derivatives such as phthalocyanine green,perylene derivatives such asdiisobutyl-4,10-dicyanoperylene-3,9-dicarboxylate; pyrromethenederivatives; stilben derivatives; oxazine derivatives; naphthalimidederivatives; pyrazine derivatives; benzimidazole derivatives;benzoxazole derivatives; benzothiazole derivatives; imidazopyridinederivatives; azole derivatives; compounds having a condensed aryl ringsuch as anthracene and derivatives thereof; aromatic amine derivatives;and organic metal complex compounds. However, the organic light-emittingmaterial (a) is not limited particularly to these examples.

Among these compounds, pyrromethene derivatives give high emissionquantum yield, are favorable in durability, and are thus particularlypreferred compounds. Among pyrromethene derivatives, a compoundrepresented by General Formula (1) below, for example, exhibits lightemission with high color purity and is thus preferred.

Preferred examples of the organic light-emitting material (a′) includelight-emitting materials similar to those for the organic light-emittingmaterial (a); the compound represented by General Formula (1) below isparticularly preferred. Preferred examples of the organic light-emittingmaterial (d) include light-emitting materials similar to those for theorganic light-emitting material (a); the compound represented by GeneralFormula (1) below is particularly preferred.

In the color conversion sheet according to the embodiment of the presentinvention, when the organic light-emitting material (a) and the organiclight-emitting material (d) are contained, both the organiclight-emitting material (a) and the organic light-emitting material (d)are preferably the compound represented by General Formula (1) below. Inthat case, the organic light-emitting material (a) and the organiclight-emitting material (d) may be the same compound or differentcompounds; in view of costs, they are more preferably the same compound.

Preferred examples of the organic light-emitting material (b) includecyanine derivatives such as4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran;rhodamine derivatives such as rhodamine B, rhodamine 6G, rhodamine 101,and sulforhodamine 101; pyridine derivatives such as1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium-perchlorate;perylene derivatives such asN,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-bis(dicarboimide);porphyrin derivatives; pyrromethene derivatives; oxazine derivatives;pyrazine derivatives; compounds having a condensed aryl ring such asnaphthacene and dibenzodiindenoperylene and derivatives thereof; andorganic metal complex compounds. However, the organic light-emittingmaterial (b) is not limited particularly to these examples.

Among these compounds, pyrromethene derivatives give high emissionquantum yield, are favorable in durability, and are thus particularlypreferred compounds. Among pyrromethene derivatives, the compoundrepresented by General Formula (1) below, for example, exhibits lightemission with high color purity and is thus preferred.

Preferred examples of the organic light-emitting material (b′) includelight-emitting materials similar to those for the organic light-emittingmaterial (b); the compound represented by General Formula (1) below isparticularly preferred. Preferred examples of the organic light-emittingmaterial (c) include light-emitting materials similar to those for theorganic light-emitting material (b); the compound represented by GeneralFormula (1) below is particularly preferred.

In the color conversion sheet according to the embodiment of the presentinvention, when the organic light-emitting material (b) and the organiclight-emitting material (c) are contained, both the organiclight-emitting material (b) and the organic light-emitting material (c)are preferably the compound represented by General Formula (1) below. Inthat case, the organic light-emitting material (b) and the organiclight-emitting material (c) may be the same compound or differentcompounds; in view of costs, they are more preferably the same compound.

(Compound Represented by General Formula (1))

In the color conversion sheet according to the embodiment of the presentinvention, at least one of the organic light-emitting material (a) andthe organic light-emitting material (b) is preferably a compoundrepresented by the following General Formula (1).

In General Formula (1), X is C—R⁷ or N. R¹ to R⁹ may be the same as ordifferent from each other and are selected from hydrogen, an alkylgroup, a cycloalkyl group, a heterocyclic group, an alkenyl group, acycloalkenyl group, an alkynyl group, a hydroxy group, a thiol group, analkoxy group, an alkylthio group, an aryl ether group, an aryl thioethergroup, an aryl group, a heteroaryl group, halogen, a cyano group, analdehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group,a carbamoyl group, an amino group, a nitro group, a silyl group, asiloxanyl group, a boryl group, a phosphine oxide group, and a condensedring formed between adjacent substituents.

In all the above groups, the hydrogen may be deuterium. This holds truefor compounds or partial structures thereof described below. In thefollowing description, a substituted or unsubstituted C₆₋₄₀ aryl group,for example, is an aryl group all the carbon number of which is 6 to 40including the carbon number included in a substituent by which the arylgroup is substituted. This holds true for other substituents definingthe carbon number.

In all the above groups, a substituent when they are substituted ispreferably an alkyl group, a cycloalkyl group, a heterocyclic group, analkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxy group,a thiol group, an alkoxy group, an alkylthio group, an aryl ether group,an aryl thioether group, an aryl group, a heteroaryl group, halogen, acyano group, an aldehyde group, a carbonyl group, a carboxy group, anoxycarbonyl group, a carbamoyl group, an amino group, a nitro group, asilyl group, a siloxanyl group, a boryl group, a phosphine oxide group,or further, a specific substituent described as preferred in thedescriptions of the respective substituents. These substituents may befurther substituted by the substituents described above.

“Unsubstituted” in “substituted or unsubstituted” means that a hydrogenatom or deuterium atom has substituted. The above holds true for casesdescribed as “substituted or unsubstituted” in the compounds or partialstructures thereof described below.

In all the above groups, the alkyl group refers to a saturated aliphatichydrocarbon group such as a methyl group, an ethyl group, a n-propylgroup, an isopropyl group, a n-butyl group, a sec-butyl group, or atert-butyl group, which optionally has a substituent. An additionalsubstituent when it is substituted is not limited to a particularsubstituent, and examples thereof include an alkyl group, halogen, anaryl group, and a heteroaryl group, which is common to the followingdescription. The carbon number of the alkyl group, which is not limitedto a particular number, is in the range of preferably 1 or more and 20or less and more preferably 1 or more and 8 or less in view ofavailability and cost.

The cycloalkyl group refers to a saturated alicyclic hydrocarbon groupsuch as a cyclopropyl group, a cyclohexyl group, a norbornyl group, oran adamantyl group, which optionally has a substituent. The carbonnumber of the alkyl group part, which is not limited to a particularnumber, is preferably in the range of 3 or more and 20 or less.

The heterocyclic group refers to an aliphatic ring having an atom otherthan carbon within its ring such as a pyran ring, a piperidine ring, ora cyclic amide, which optionally has a substituent. The carbon number ofthe heterocyclic group, which is not limited to a particular number, ispreferably in the range of 2 or more and 20 or less.

The alkenyl group refers to an unsaturated aliphatic hydrocarbon groupcontaining a double bond such as a vinyl group, an allyl group, or abutadienyl group, which optionally has a substituent. The carbon numberof the alkenyl group, which is not limited to a particular number, ispreferably in the range of 2 or more and 20 or less.

The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbongroup containing a double bond such as a cyclopentenyl group, acyclopentadienyl group, or a cyclohexenyl group, which optionally has asubstituent.

The alkynyl group refers to an unsaturated aliphatic hydrocarbon groupcontaining a triple bond such as an ethynyl group, which optionally hasa substituent. The carbon number of the alkynyl group, which is notlimited to a particular number, is preferably in the range of 2 or moreand 20 or less.

The alkoxy group refers to a functional group to which an aliphatichydrocarbon group bonds through an ether bond such as a methoxy group,an ethoxy group, or a propoxy group, and this aliphatic hydrocarbongroup optionally has a substituent. The carbon number of the alkoxygroup, which is not limited to a particular number, is preferably in therange of 1 or more and 20 or less.

The alkylthio group is a group in which the oxygen atom of the etherbond of the alkoxy group is substituted by a sulfur atom. Thehydrocarbon group of the alkylthio group optionally has a substituent.The carbon number of the alkylthio group, which is not limited to aparticular number, is preferably in the range of 1 or more and 20 orless.

The aryl ether group refers to a function group to which an aromatichydrocarbon group bonds through an ether bond such as a phenoxy group,and the aromatic hydrocarbon group optionally has a substituent. Thecarbon number of the aryl ether group, which is not limited to aparticular number, is preferably in the range of 6 or more and 40 orless.

The aryl thioether group is a group in which the oxygen atom of theether bond of the aryl ether group is substituted by a sulfur atom. Thearomatic hydrocarbon group of the aryl thioether group optionally has asubstituent. The carbon number of the aryl thioether group, which is notlimited to a particular number, is preferably in the range of 6 or moreand 40 or less.

The aryl group refers to an aromatic hydrocarbon group such as a phenylgroup, a biphenyl group, a terphenyl group, a naphthyl group, afluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, aphenanthryl group, an anthracenyl group, a benzophenanthryl group, abenzoanthracenyl group, a crycenyl group, a pyrenyl group, afluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group,a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group.Among them, preferred are a phenyl group, a biphenyl group, a terphenylgroup, a naphthyl group, a fluorenyl group, a phenanthryl group, ananthracenyl group, a pyrenyl group, a fluoranthenyl group, and atriphenylenyl group. The aryl group optionally has a substituent. Thecarbon number of the aryl group, which is not limited to a particularnumber, is in the range of preferably 6 or more and 40 or less and morepreferably 6 or more and 30 or less.

When R¹ to R⁹ are each a substituted or unsubstituted aryl group, thearyl group is preferably a phenyl group, a biphenyl group, a terphenylgroup, a naphthyl group, a fluorenyl group, a phenanthryl group, or ananthracenyl group, more preferably a phenyl group, a biphenyl group, aterphenyl group, or a naphthyl group, further preferably a phenyl group,a biphenyl group, or a terphenyl group, and particularly preferably aphenyl group.

When each of the substituents is further substituted by an aryl group,the aryl group is preferably a phenyl group, a biphenyl group, aterphenyl group, a naphthyl group, a fluorenyl group, a phenanthrylgroup, or an anthracenyl group, more preferably a phenyl group, abiphenyl group, a terphenyl group, or a naphthyl group, and particularlypreferably a phenyl group.

The heteroaryl group refers to a cyclic aromatic group having one ormore atoms other than carbon within its ring such as a pyridyl group, afuranyl group, a thienyl group, a quinolinyl group, an isoquinolinylgroup, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, atriazinyl group, a naphthyridinyl group, a cinnolinyl group, aphthalazinyl group, a quinoxalinyl group, a quinazolinyl group, abenzofuranyl group, a benzothienyl group, an indolyl group, adibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, abenzocarbazolyl group, a carbolinyl group, an indolocarbazolyl group, abenzofurocarbazolyl group, a benzothienocarbazolyl group, adihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinylgroup, a dibenzoacridinyl group, a benzimidazolyl group, animidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or aphenanthrolinyl group. The naphthyridinyl group refers to any of a1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a2,6-naphthyridinyl group, or a 2,7-naphthyridinyl group. The heteroarylgroup optionally has a substituent. The carbon number of the heteroarylgroup, which is not limited to a particular number, is in the range ofpreferably 2 or more and 40 or less and more preferably 2 or more and 30or less.

When R¹ to R⁹ are each a substituted or unsubstituted heteroaryl group,the heteroaryl group is preferably a pyridyl group, a furanyl group, athienyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group,a benzofuranyl group, a benzothienyl group, an indolyl group, adibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, abenzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, abenzothiazolyl group, or a phenanthrolinyl group, more preferably apyridyl group, a furanyl group, a thienyl group, or a quinolinyl group,and particularly preferably a pyridyl group.

When each of the substituents is further substituted by a heteroarylgroup, the heteroaryl group is preferably a pyridyl group, a furanylgroup, a thienyl group, a quinolinyl group, a pyrimidyl group, atriazinyl group, a benzofuranyl group, a benzothienyl group, an indolylgroup, a dibenzofuranyl group, a dibenzothienyl group, a carbazolylgroup, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolylgroup, a benzothiazolyl group, or a phenanthrolinyl group, morepreferably a pyridyl group, a furanyl group, a thienyl group, or aquinolinyl group, and particularly preferably a pyridyl group.

The halogen refers to an atom selected from fluorine, chlorine, bromine,and iodine. The carbonyl group, the carboxy group, the oxycarbonylgroup, and the carbamoyl group each optionally have a substituent.Examples of the substituent include an alkyl group, a cycloalkyl group,an aryl group, and a heteroaryl group, and these substituents may befurther substituted.

The amino group is a substituted or unsubstituted amino group. Examplesof the substituent when it is substituted include an aryl group, aheteroaryl group, a linear alkyl group, and a branched alkyl group. Thearyl group and the heteroaryl group are preferably a phenyl group, anaphthyl group, a pyridyl group, or a quinolinyl group. Thesesubstituents may be further substituted. The carbon number, which is notlimited to a particular number, is in the range of preferably 2 or moreand 50 or less, more preferably 6 or more and 40 or less, andparticularly preferably 6 or more and 30 or less.

The silyl group refers to an alkyl silyl group such as a trimethylsilylgroup, a triethylsilyl group, a tert-butyl dimethyl silyl group, apropyl dimethyl silyl group, or a vinyl dimethyl silyl group and an arylsilyl group such as a phenyl dimethyl silyl group, a tert-butyl diphenylsilyl group, a triphenyl silyl group, or a trinaphthyl silyl group. Thesubstituent on the silicon may be further substituted. The carbon numberof the silyl group, which is not limited to a particular number, ispreferably in the range of 1 or more and 30 or less.

The siloxanyl group refers to a silicide group through an ether bondsuch as trimethylsiloxanyl group. The substituent on the silicon may befurther substituted. The boryl group is a substituted or unsubstitutedboryl group. Examples of a substituent when it is substituted include anaryl group, a heteroaryl group, a linear alkyl group, a branched alkylgroup, an aryl ether group, an alkoxy group, and a hydroxy group. Amongthem, preferred are an aryl group and an aryl ether group. The phosphineoxide group is a group represented by —P(═O)R¹⁰R¹¹. R¹⁰ and R¹¹ are eachselected from a group similar to that for R¹ to R⁹.

The condensed ring and the aliphatic ring formed between adjacentsubstituents refers to mutual bonding between any two adjacentsubstituents (R¹ and R² in General Formula (1), for example) forming aconjugated or non-conjugated cyclic skeleton. As the element of thecondensed ring and the aliphatic ring, an element selected fromnitrogen, oxygen, sulfur, phosphorous, and silicon, besides carbon, maybe contained. The condensed ring and the aliphatic ring may furthercondense with another ring.

The compound represented by General Formula (1) exhibits high emissionquantum yield and is small in the full width at half maximum of anemission spectrum, thus enabling both efficient color conversion andhigh color purity to be achieved. In addition, the compound representedby General Formula (1), by introducing an appropriate substituent to anappropriate position, enables various characteristics and propertiessuch as emission efficiency, color purity, thermal stability,photostability, and dispersibility to be adjusted. A case in which atleast one of R¹, R³, R⁴, and R⁶ is a substituted or unsubstituted alkylgroup, a substituted or unsubstituted aryl group, or a substituted orunsubstituted heteroaryl group exhibits better thermal stability andphotostability compared with a case in which all R¹, R³, R⁴, and R⁶ arehydrogens, for example.

When at least one of R¹, R³, R⁴, and R⁶ is a substituted orunsubstituted alkyl group, the alkyl group is preferably a C₁₋₆ alkylgroup such as a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group,a pentyl group, or a hexyl group. In addition, this alkyl group ispreferably a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, a sec-butyl group, or a tert-butylgroup in view of being excellent in thermal stability. In view ofpreventing concentration quenching to improve fluorescence quantumyield, this alkyl group is more preferably a tert-butyl group, which issterically bulky. In view of the easiness of synthesis and raw materialavailability, this alkyl group is also preferably a methyl group.

When at least one of R¹, R³, R⁴, and R⁶ is a substituted orunsubstituted aryl group, the aryl group is preferably a phenyl group, abiphenyl group, a terphenyl group, or a naphthyl group, furtherpreferably a phenyl group or a biphenyl group, and particularlypreferably a phenyl group.

When at least one of R¹, R³, R⁴, and R⁶ is a substituted orunsubstituted heteroaryl group, the heteroaryl group is preferably apyridyl group, a quinolinyl group, or a thienyl group, furtherpreferably a pyridyl group or a quinolinyl group, and particularlypreferably a pyridyl group.

When all R¹, R³, R⁴, and R⁶ may be the same as or different from eachother and are substituted or unsubstituted alkyl groups, solubility to abinder resin or a solvent is favorable, which is preferred. In thiscase, the alkyl group is preferably a methyl group in view of theeasiness of synthesis and raw material availability.

When all R¹, R³, R⁴, and R⁶, which may be the same as or different fromeach other, are substituted or unsubstituted aryl groups or substitutedor unsubstituted heteroaryl groups, better thermal stability andphotostability are exhibited, which is preferred. In this case, all R¹,R³, R⁴, and R⁶, which may be the same as or different from each other,are more preferably substituted or unsubstituted aryl groups.

Although some substituents improve a plurality of properties,substituents that exhibit sufficient performance in all are limited. Inparticular, it is difficult to achieve both high emission efficiency andhigh color purity. Given these circumstances, a plurality of kinds ofsubstituents are introduced to the compound represented by GeneralFormula (1), whereby a compound having a balance among emissioncharacteristics, high color purity, and the like can be obtained.

In particular, when all R¹, R³, R⁴, and R⁶, which may be the same as ordifferent from each other, are substituted or unsubstituted aryl groups,a plurality of kinds of substituents are preferably introduced, such asR¹≠R⁴, R³≠R⁶, R¹≠R³, or R⁴≠R⁶. In this example, “≠” means that they aregroups having different structures. R¹≠R⁴ means that R¹ and R⁴ aregroups having different structures, for example. A plurality of kinds ofsubstituents are introduced as described above, whereby an aryl groupthat has an influence on color purity and an aryl group that has aninfluence on emission efficiency can be simultaneously introduced, andfine adjustment can be made.

Among them, R¹≠R³ or R⁴≠R⁶ is preferred in view of improving emissionefficiency and color purity with a good balance. In this case, to thecompound represented by General Formula (1), one or more aryl groupshaving an influence on color purity can be introduced to both pyrrolerings each, whereas an aryl group having an influence on emissionefficiency can be introduced to any other position, and both of theseproperties can be improved to the maximum. In addition, when R¹≠R³ orR⁴≠R⁶, in view of improving both heat resistance and color purity, morepreferred are R¹≠R⁴ and R³═R⁶.

The aryl group that has an influence mainly on color purity ispreferably an aryl group substituted by an electron donating group. Theelectron donating group is an atomic group that donates an electron to asubstituted atomic group by the inductive effect and/or the resonanceeffect in the organic electron theory. Examples of the electron donatinggroup include ones having a negative value as a substituent constant (σp(para)) of Hammett's Rule. The substituent constant (σp (para)) ofHammett's Rule can be cited from Kagaku Binran Kiso-Hen Revised 5thEdition (II, p. 380).

Specific examples of the electron donating group include an alkyl group(σp of a methyl group: −0.17), an alkoxy group (σp of a methoxygroup=−0.27), and an amino group (σp of —NH₂=−0.66). In particular, aC₁₋₈ alkyl group or a C₁₋₈ alkoxy group is preferred, and more preferredare a methyl group, an ethyl group, a tert-butyl group, and a methoxygroup. In view of dispersibility, a tert-butyl group and a methoxy groupare particularly preferred; when these substituents are the electrondonating group, quenching caused by the flocculation of molecules can beprevented in the compound represented by General Formula (1). Althoughthe substitution position of the substituent is not limited to aparticular position, the substituent is preferably bonded to the metaposition or the para position relative to the position bonding to thepyrromethene skeleton, because the twist of bonding is required to beinhibited in order to increase the photostability of the compoundrepresented by General Formula (1). Meanwhile, the aryl group that hasan influence mainly on emission efficiency is preferably an aryl grouphaving a bulky substituent such as a tert-butyl group, an adamantylgroup, or a methoxy group.

When R¹, R³, R⁴, and R⁶, which may be the same as or different from eachother, are substituted or unsubstituted aryl groups, R¹, R³, R⁴, and R⁶,which may be the same as or different from each other, are preferablysubstituted or unsubstituted phenyl groups. In this case, R¹, R³, R⁴,and R⁶ are each more preferably selected from the following Ar-1 toAr-6. In this case, examples of a preferred combination of R¹, R³, R⁴,and R⁶ include, but are not limited to, combinations listed in Table 1-1to Table 1-11.

TABLE 1-1 R1 R3 R4 R6 Ar-1 Ar-1 Ar-1 Ar-1 Ar-1 Ar-1 Ar-1 Ar-2 Ar-1 Ar-1Ar-1 Ar-3 Ar-1 Ar-1 Ar-1 Ar-4 Ar-1 Ar-1 Ar-1 Ar-5 Ar-1 Ar-1 Ar-1 Ar-6Ar-1 Ar-1 Ar-2 Ar-1 Ar-1 Ar-1 Ar-2 Ar-2 Ar-1 Ar-1 Ar-2 Ar-3 Ar-1 Ar-1Ar-2 Ar-4 Ar-1 Ar-1 Ar-2 Ar-5 Ar-1 Ar-1 Ar-2 Ar-6 Ar-1 Ar-1 Ar-3 Ar-1Ar-1 Ar-1 Ar-3 Ar-2 Ar-1 Ar-1 Ar-3 Ar-3 Ar-1 Ar-1 Ar-3 Ar-4 Ar-1 Ar-1Ar-3 Ar-5 Ar-1 Ar-1 Ar-3 Ar-6 Ar-1 Ar-1 Ar-4 Ar-1 Ar-1 Ar-1 Ar-4 Ar-2Ar-1 Ar-1 Ar-4 Ar-3 Ar-1 Ar-1 Ar-4 Ar-4 Ar-1 Ar-1 Ar-4 Ar-5 Ar-1 Ar-1Ar-4 Ar-6 Ar-1 Ar-1 Ar-5 Ar-1 Ar-1 Ar-1 Ar-5 Ar-2 Ar-1 Ar-1 Ar-5 Ar-3Ar-1 Ar-1 Ar-5 Ar-4 Ar-1 Ar-1 Ar-5 Ar-5 Ar-1 Ar-1 Ar-5 Ar-6 Ar-1 Ar-1Ar-6 Ar-1 Ar-1 Ar-1 Ar-6 Ar-2 Ar-1 Ar-1 Ar-6 Ar-3 Ar-1 Ar-1 Ar-6 Ar-4Ar-1 Ar-1 Ar-6 Ar-5 Ar-1 Ar-1 Ar-6 Ar-6 Ar-1 Ar-2 Ar-1 Ar-2 Ar-1 Ar-2Ar-1 Ar-3 Ar-1 Ar-2 Ar-1 Ar-4 Ar-1 Ar-2 Ar-1 Ar-5 Ar-1 Ar-2 Ar-1 Ar-6Ar-1 Ar-2 Ar-2 Ar-1 Ar-1 Ar-2 Ar-2 Ar-2 Ar-1 Ar-2 Ar-2 Ar-3 Ar-1 Ar-2Ar-2 Ar-4 Ar-1 Ar-2 Ar-2 Ar-5 Ar-1 Ar-2 Ar-2 Ar-6 Ar-1 Ar-2 Ar-3 Ar-1Ar-1 Ar-2 Ar-3 Ar-2 Ar-1 Ar-2 Ar-3 Ar-3 Ar-1 Ar-2 Ar-3 Ar-4 Ar-1 Ar-2Ar-3 Ar-5 Ar-1 Ar-2 Ar-3 Ar-6 Ar-1 Ar-2 Ar-4 Ar-1 Ar-1 Ar-2 Ar-4 Ar-2Ar-1 Ar-2 Ar-4 Ar-3 Ar-1 Ar-2 Ar-4 Ar-4 Ar-1 Ar-2 Ar-4 Ar-5 Ar-1 Ar-2Ar-4 Ar-6

TABLE 1-2 R1 R3 R4 R6 Ar-1 Ar-2 Ar-5 Ar-1 Ar-1 Ar-2 Ar-5 Ar-2 Ar-1 Ar-2Ar-5 Ar-3 Ar-1 Ar-2 Ar-5 Ar-4 Ar-1 Ar-2 Ar-5 Ar-5 Ar-1 Ar-2 Ar-5 Ar-6Ar-1 Ar-2 Ar-6 Ar-1 Ar-1 Ar-2 Ar-6 Ar-2 Ar-1 Ar-2 Ar-6 Ar-3 Ar-1 Ar-2Ar-6 Ar-4 Ar-1 Ar-2 Ar-6 Ar-5 Ar-1 Ar-2 Ar-6 Ar-6 Ar-1 Ar-3 Ar-1 Ar-2Ar-1 Ar-3 Ar-1 Ar-3 Ar-1 Ar-3 Ar-1 Ar-4 Ar-1 Ar-3 Ar-1 Ar-5 Ar-1 Ar-3Ar-1 Ar-6 Ar-1 Ar-3 Ar-2 Ar-2 Ar-1 Ar-3 Ar-2 Ar-3 Ar-1 Ar-3 Ar-2 Ar-4Ar-1 Ar-3 Ar-2 Ar-5 Ar-1 Ar-3 Ar-2 Ar-6 Ar-1 Ar-3 Ar-3 Ar-1 Ar-1 Ar-3Ar-3 Ar-2 Ar-1 Ar-3 Ar-3 Ar-3 Ar-1 Ar-3 Ar-3 Ar-4 Ar-1 Ar-3 Ar-3 Ar-5Ar-1 Ar-3 Ar-3 Ar-6 Ar-1 Ar-3 Ar-4 Ar-1 Ar-1 Ar-3 Ar-4 Ar-2 Ar-1 Ar-3Ar-4 Ar-3 Ar-1 Ar-3 Ar-4 Ar-4 Ar-1 Ar-3 Ar-4 Ar-5 Ar-1 Ar-3 Ar-4 Ar-6Ar-1 Ar-3 Ar-5 Ar-1 Ar-1 Ar-3 Ar-5 Ar-2 Ar-1 Ar-3 Ar-5 Ar-3 Ar-1 Ar-3Ar-5 Ar-4 Ar-1 Ar-3 Ar-5 Ar-5 Ar-1 Ar-3 Ar-5 Ar-6 Ar-1 Ar-3 Ar-6 Ar-1Ar-1 Ar-3 Ar-6 Ar-2 Ar-1 Ar-3 Ar-6 Ar-3 Ar-1 Ar-3 Ar-6 Ar-4 Ar-1 Ar-3Ar-6 Ar-5 Ar-1 Ar-3 Ar-6 Ar-6 Ar-1 Ar-4 Ar-1 Ar-2 Ar-1 Ar-4 Ar-1 Ar-3Ar-1 Ar-4 Ar-1 Ar-4 Ar-1 Ar-4 Ar-1 Ar-5 Ar-1 Ar-4 Ar-1 Ar-6 Ar-1 Ar-4Ar-2 Ar-2 Ar-1 Ar-4 Ar-2 Ar-3 Ar-1 Ar-4 Ar-2 Ar-4 Ar-1 Ar-4 Ar-2 Ar-5Ar-1 Ar-4 Ar-2 Ar-6 Ar-1 Ar-4 Ar-3 Ar-2 Ar-1 Ar-4 Ar-3 Ar-3 Ar-1 Ar-4Ar-3 Ar-4 Ar-1 Ar-4 Ar-3 Ar-5 Ar-1 Ar-4 Ar-3 Ar-6

TABLE 1-3 R1 R3 R4 R6 Ar-1 Ar-4 Ar-4 Ar-1 Ar-1 Ar-4 Ar-4 Ar-2 Ar-1 Ar-4Ar-4 Ar-3 Ar-1 Ar-4 Ar-4 Ar-4 Ar-1 Ar-4 Ar-4 Ar-5 Ar-1 Ar-4 Ar-4 Ar-6Ar-1 Ar-4 Ar-5 Ar-1 Ar-1 Ar-4 Ar-5 Ar-2 Ar-1 Ar-4 Ar-5 Ar-3 Ar-1 Ar-4Ar-5 Ar-4 Ar-1 Ar-4 Ar-5 Ar-5 Ar-1 Ar-4 Ar-5 Ar-6 Ar-1 Ar-4 Ar-6 Ar-1Ar-1 Ar-4 Ar-6 Ar-2 Ar-1 Ar-4 Ar-6 Ar-3 Ar-1 Ar-4 Ar-6 Ar-4 Ar-1 Ar-4Ar-6 Ar-5 Ar-1 Ar-4 Ar-6 Ar-6 Ar-1 Ar-5 Ar-1 Ar-2 Ar-1 Ar-5 Ar-1 Ar-3Ar-1 Ar-5 Ar-1 Ar-4 Ar-1 Ar-5 Ar-1 Ar-5 Ar-1 Ar-5 Ar-1 Ar-6 Ar-1 Ar-5Ar-2 Ar-2 Ar-1 Ar-5 Ar-2 Ar-3 Ar-1 Ar-5 Ar-2 Ar-4 Ar-1 Ar-5 Ar-2 Ar-5Ar-1 Ar-5 Ar-2 Ar-6 Ar-1 Ar-5 Ar-3 Ar-2 Ar-1 Ar-5 Ar-3 Ar-3 Ar-1 Ar-5Ar-3 Ar-4 Ar-1 Ar-5 Ar-3 Ar-5 Ar-1 Ar-5 Ar-3 Ar-6 Ar-1 Ar-5 Ar-4 Ar-2Ar-1 Ar-5 Ar-4 Ar-3 Ar-1 Ar-5 Ar-4 Ar-4 Ar-1 Ar-5 Ar-4 Ar-5 Ar-1 Ar-5Ar-4 Ar-6 Ar-1 Ar-5 Ar-5 Ar-1 Ar-1 Ar-5 Ar-5 Ar-2 Ar-1 Ar-5 Ar-5 Ar-3Ar-1 Ar-5 Ar-5 Ar-4 Ar-1 Ar-5 Ar-5 Ar-5 Ar-1 Ar-5 Ar-5 Ar-6 Ar-1 Ar-5Ar-6 Ar-1 Ar-1 Ar-5 Ar-6 Ar-2 Ar-1 Ar-5 Ar-6 Ar-3 Ar-1 Ar-5 Ar-6 Ar-4Ar-1 Ar-5 Ar-6 Ar-5 Ar-1 Ar-5 Ar-6 Ar-6 Ar-1 Ar-6 Ar-1 Ar-2 Ar-1 Ar-6Ar-1 Ar-3 Ar-1 Ar-6 Ar-1 Ar-4 Ar-1 Ar-6 Ar-1 Ar-5 Ar-1 Ar-6 Ar-1 Ar-6Ar-1 Ar-6 Ar-2 Ar-2 Ar-1 Ar-6 Ar-2 Ar-3 Ar-1 Ar-6 Ar-2 Ar-4 Ar-1 Ar-6Ar-2 Ar-5 Ar-1 Ar-6 Ar-2 Ar-6

TABLE 1-4 R1 R3 R4 R6 Ar-1 Ar-6 Ar-3 Ar-2 Ar-1 Ar-6 Ar-3 Ar-3 Ar-1 Ar-6Ar-3 Ar-4 Ar-1 Ar-6 Ar-3 Ar-5 Ar-1 Ar-6 Ar-3 Ar-6 Ar-1 Ar-6 Ar-4 Ar-2Ar-1 Ar-6 Ar-4 Ar-3 Ar-1 Ar-6 Ar-4 Ar-4 Ar-1 Ar-6 Ar-4 Ar-5 Ar-1 Ar-6Ar-4 Ar-6 Ar-1 Ar-6 Ar-5 Ar-2 Ar-1 Ar-6 Ar-5 Ar-3 Ar-1 Ar-6 Ar-5 Ar-4Ar-1 Ar-6 Ar-5 Ar-5 Ar-1 Ar-6 Ar-5 Ar-6 Ar-1 Ar-6 Ar-6 Ar-1 Ar-1 Ar-6Ar-6 Ar-2 Ar-1 Ar-6 Ar-6 Ar-3 Ar-1 Ar-6 Ar-6 Ar-4 Ar-1 Ar-6 Ar-6 Ar-5Ar-1 Ar-6 Ar-6 Ar-6 Ar-2 Ar-1 Ar-1 Ar-2 Ar-2 Ar-1 Ar-1 Ar-3 Ar-2 Ar-1Ar-1 Ar-4 Ar-2 Ar-1 Ar-1 Ar-5 Ar-2 Ar-1 Ar-1 Ar-6 Ar-2 Ar-1 Ar-2 Ar-2Ar-2 Ar-1 Ar-2 Ar-3 Ar-2 Ar-1 Ar-2 Ar-4 Ar-2 Ar-1 Ar-2 Ar-5 Ar-2 Ar-1Ar-2 Ar-6 Ar-2 Ar-1 Ar-3 Ar-2 Ar-2 Ar-1 Ar-3 Ar-3 Ar-2 Ar-1 Ar-3 Ar-4Ar-2 Ar-1 Ar-3 Ar-5 Ar-2 Ar-1 Ar-3 Ar-6 Ar-2 Ar-1 Ar-4 Ar-2 Ar-2 Ar-1Ar-4 Ar-3 Ar-2 Ar-1 Ar-4 Ar-4 Ar-2 Ar-1 Ar-4 Ar-5 Ar-2 Ar-1 Ar-4 Ar-6Ar-2 Ar-1 Ar-5 Ar-2 Ar-2 Ar-1 Ar-5 Ar-3 Ar-2 Ar-1 Ar-5 Ar-4 Ar-2 Ar-1Ar-5 Ar-5 Ar-2 Ar-1 Ar-5 Ar-6 Ar-2 Ar-1 Ar-6 Ar-2 Ar-2 Ar-1 Ar-6 Ar-3Ar-2 Ar-1 Ar-6 Ar-4 Ar-2 Ar-1 Ar-6 Ar-5 Ar-2 Ar-1 Ar-6 Ar-6 Ar-2 Ar-2Ar-1 Ar-3 Ar-2 Ar-2 Ar-1 Ar-4 Ar-2 Ar-2 Ar-1 Ar-5 Ar-2 Ar-2 Ar-1 Ar-6Ar-2 Ar-2 Ar-2 Ar-2 Ar-2 Ar-2 Ar-2 Ar-3 Ar-2 Ar-2 Ar-2 Ar-4 Ar-2 Ar-2Ar-2 Ar-5 Ar-2 Ar-2 Ar-2 Ar-6

TABLE 1-5 R1 R3 R4 R6 Ar-2 Ar-2 Ar-3 Ar-2 Ar-2 Ar-2 Ar-3 Ar-3 Ar-2 Ar-2Ar-3 Ar-4 Ar-2 Ar-2 Ar-3 Ar-5 Ar-2 Ar-2 Ar-3 Ar-6 Ar-2 Ar-2 Ar-4 Ar-2Ar-2 Ar-2 Ar-4 Ar-3 Ar-2 Ar-2 Ar-4 Ar-4 Ar-2 Ar-2 Ar-4 Ar-5 Ar-2 Ar-2Ar-4 Ar-6 Ar-2 Ar-2 Ar-5 Ar-2 Ar-2 Ar-2 Ar-5 Ar-3 Ar-2 Ar-2 Ar-5 Ar-4Ar-2 Ar-2 Ar-5 Ar-5 Ar-2 Ar-2 Ar-5 Ar-6 Ar-2 Ar-2 Ar-6 Ar-2 Ar-2 Ar-2Ar-6 Ar-3 Ar-2 Ar-2 Ar-6 Ar-4 Ar-2 Ar-2 Ar-6 Ar-5 Ar-2 Ar-2 Ar-6 Ar-6Ar-2 Ar-3 Ar-1 Ar-3 Ar-2 Ar-3 Ar-1 Ar-4 Ar-2 Ar-3 Ar-1 Ar-5 Ar-2 Ar-3Ar-1 Ar-6 Ar-2 Ar-3 Ar-2 Ar-3 Ar-2 Ar-3 Ar-2 Ar-4 Ar-2 Ar-3 Ar-2 Ar-5Ar-2 Ar-3 Ar-2 Ar-6 Ar-2 Ar-3 Ar-3 Ar-2 Ar-2 Ar-3 Ar-3 Ar-3 Ar-2 Ar-3Ar-3 Ar-4 Ar-2 Ar-3 Ar-3 Ar-5 Ar-2 Ar-3 Ar-3 Ar-6 Ar-2 Ar-3 Ar-4 Ar-2Ar-2 Ar-3 Ar-4 Ar-3 Ar-2 Ar-3 Ar-4 Ar-4 Ar-2 Ar-3 Ar-4 Ar-5 Ar-2 Ar-3Ar-4 Ar-6 Ar-2 Ar-3 Ar-5 Ar-2 Ar-2 Ar-3 Ar-5 Ar-3 Ar-2 Ar-3 Ar-5 Ar-4Ar-2 Ar-3 Ar-5 Ar-5 Ar-2 Ar-3 Ar-5 Ar-6 Ar-2 Ar-3 Ar-6 Ar-2 Ar-2 Ar-3Ar-6 Ar-3 Ar-2 Ar-3 Ar-6 Ar-4 Ar-2 Ar-3 Ar-6 Ar-5 Ar-2 Ar-3 Ar-6 Ar-6Ar-2 Ar-4 Ar-1 Ar-3 Ar-2 Ar-4 Ar-1 Ar-4 Ar-2 Ar-4 Ar-1 Ar-5 Ar-2 Ar-4Ar-1 Ar-6 Ar-2 Ar-4 Ar-2 Ar-3 Ar-2 Ar-4 Ar-2 Ar-4 Ar-2 Ar-4 Ar-2 Ar-5Ar-2 Ar-4 Ar-2 Ar-6 Ar-2 Ar-4 Ar-3 Ar-3 Ar-2 Ar-4 Ar-3 Ar-4 Ar-2 Ar-4Ar-3 Ar-5 Ar-2 Ar-4 Ar-3 Ar-6

TABLE 1-6 R1 R3 R4 R6 Ar-2 Ar-4 Ar-4 Ar-2 Ar-2 Ar-4 Ar-4 Ar-3 Ar-2 Ar-4Ar-4 Ar-4 Ar-2 Ar-4 Ar-4 Ar-5 Ar-2 Ar-4 Ar-4 Ar-6 Ar-2 Ar-4 Ar-5 Ar-2Ar-2 Ar-4 Ar-5 Ar-3 Ar-2 Ar-4 Ar-5 Ar-4 Ar-2 Ar-4 Ar-5 Ar-5 Ar-2 Ar-4Ar-5 Ar-6 Ar-2 Ar-4 Ar-6 Ar-2 Ar-2 Ar-4 Ar-6 Ar-3 Ar-2 Ar-4 Ar-6 Ar-4Ar-2 Ar-4 Ar-6 Ar-5 Ar-2 Ar-4 Ar-6 Ar-6 Ar-2 Ar-5 Ar-1 Ar-3 Ar-2 Ar-5Ar-1 Ar-4 Ar-2 Ar-5 Ar-1 Ar-5 Ar-2 Ar-5 Ar-1 Ar-6 Ar-2 Ar-5 Ar-2 Ar-3Ar-2 Ar-5 Ar-2 Ar-4 Ar-2 Ar-5 Ar-2 Ar-5 Ar-2 Ar-5 Ar-2 Ar-6 Ar-2 Ar-5Ar-3 Ar-3 Ar-2 Ar-5 Ar-3 Ar-4 Ar-2 Ar-5 Ar-3 Ar-5 Ar-2 Ar-5 Ar-3 Ar-6Ar-2 Ar-5 Ar-4 Ar-3 Ar-2 Ar-5 Ar-4 Ar-4 Ar-2 Ar-5 Ar-4 Ar-5 Ar-2 Ar-5Ar-4 Ar-6 Ar-2 Ar-5 Ar-5 Ar-2 Ar-2 Ar-5 Ar-5 Ar-3 Ar-2 Ar-5 Ar-5 Ar-4Ar-2 Ar-5 Ar-5 Ar-5 Ar-2 Ar-5 Ar-5 Ar-6 Ar-2 Ar-5 Ar-6 Ar-2 Ar-2 Ar-5Ar-6 Ar-3 Ar-2 Ar-5 Ar-6 Ar-4 Ar-2 Ar-5 Ar-6 Ar-5 Ar-2 Ar-5 Ar-6 Ar-6Ar-2 Ar-6 Ar-1 Ar-3 Ar-2 Ar-6 Ar-1 Ar-4 Ar-2 Ar-6 Ar-1 Ar-5 Ar-2 Ar-6Ar-1 Ar-6 Ar-2 Ar-6 Ar-2 Ar-3 Ar-2 Ar-6 Ar-2 Ar-4 Ar-2 Ar-6 Ar-2 Ar-5Ar-2 Ar-6 Ar-2 Ar-6 Ar-2 Ar-6 Ar-3 Ar-3 Ar-2 Ar-6 Ar-3 Ar-4 Ar-2 Ar-6Ar-3 Ar-5 Ar-2 Ar-6 Ar-3 Ar-6 Ar-2 Ar-6 Ar-4 Ar-3 Ar-2 Ar-6 Ar-4 Ar-4Ar-2 Ar-6 Ar-4 Ar-5 Ar-2 Ar-6 Ar-4 Ar-6 Ar-2 Ar-6 Ar-5 Ar-3 Ar-2 Ar-6Ar-5 Ar-4 Ar-2 Ar-6 Ar-5 Ar-5 Ar-2 Ar-6 Ar-5 Ar-6

TABLE 1-7 R1 R3 R4 R6 Ar-2 Ar-6 Ar-6 Ar-2 Ar-2 Ar-6 Ar-6 Ar-3 Ar-2 Ar-6Ar-6 Ar-4 Ar-2 Ar-6 Ar-6 Ar-5 Ar-2 Ar-6 Ar-6 Ar-6 Ar-3 Ar-1 Ar-1 Ar-3Ar-3 Ar-1 Ar-1 Ar-4 Ar-3 Ar-1 Ar-1 Ar-5 Ar-3 Ar-1 Ar-1 Ar-6 Ar-3 Ar-1Ar-2 Ar-3 Ar-3 Ar-1 Ar-2 Ar-4 Ar-3 Ar-1 Ar-2 Ar-5 Ar-3 Ar-1 Ar-2 Ar-6Ar-3 Ar-1 Ar-3 Ar-3 Ar-3 Ar-1 Ar-3 Ar-4 Ar-3 Ar-1 Ar-3 Ar-5 Ar-3 Ar-1Ar-3 Ar-6 Ar-3 Ar-1 Ar-4 Ar-3 Ar-3 Ar-1 Ar-4 Ar-4 Ar-3 Ar-1 Ar-4 Ar-5Ar-3 Ar-1 Ar-4 Ar-6 Ar-3 Ar-1 Ar-5 Ar-3 Ar-3 Ar-1 Ar-5 Ar-4 Ar-3 Ar-1Ar-5 Ar-5 Ar-3 Ar-1 Ar-5 Ar-6 Ar-3 Ar-1 Ar-6 Ar-3 Ar-3 Ar-1 Ar-6 Ar-4Ar-3 Ar-1 Ar-6 Ar-5 Ar-3 Ar-1 Ar-6 Ar-6 Ar-3 Ar-2 Ar-1 Ar-4 Ar-3 Ar-2Ar-1 Ar-5 Ar-3 Ar-2 Ar-1 Ar-6 Ar-3 Ar-2 Ar-2 Ar-3 Ar-3 Ar-2 Ar-2 Ar-4Ar-3 Ar-2 Ar-2 Ar-5 Ar-3 Ar-2 Ar-2 Ar-6 Ar-3 Ar-2 Ar-3 Ar-3 Ar-3 Ar-2Ar-3 Ar-4 Ar-3 Ar-2 Ar-3 Ar-5 Ar-3 Ar-2 Ar-3 Ar-6 Ar-3 Ar-2 Ar-4 Ar-3Ar-3 Ar-2 Ar-4 Ar-4 Ar-3 Ar-2 Ar-4 Ar-5 Ar-3 Ar-2 Ar-4 Ar-6 Ar-3 Ar-2Ar-5 Ar-3 Ar-3 Ar-2 Ar-5 Ar-4 Ar-3 Ar-2 Ar-5 Ar-5 Ar-3 Ar-2 Ar-5 Ar-6Ar-3 Ar-2 Ar-6 Ar-3 Ar-3 Ar-2 Ar-6 Ar-4 Ar-3 Ar-2 Ar-6 Ar-5 Ar-3 Ar-2Ar-6 Ar-6 Ar-3 Ar-3 Ar-1 Ar-4 Ar-3 Ar-3 Ar-1 Ar-5 Ar-3 Ar-3 Ar-1 Ar-6Ar-3 Ar-3 Ar-2 Ar-4 Ar-3 Ar-3 Ar-2 Ar-5 Ar-3 Ar-3 Ar-2 Ar-6 Ar-3 Ar-3Ar-3 Ar-3 Ar-3 Ar-3 Ar-3 Ar-4 Ar-3 Ar-3 Ar-3 Ar-5

TABLE 1-8 R1 R3 R4 R6 Ar-3 Ar-3 Ar-3 Ar-6 Ar-3 Ar-3 Ar-4 Ar-3 Ar-3 Ar-3Ar-4 Ar-4 Ar-3 Ar-3 Ar-4 Ar-5 Ar-3 Ar-3 Ar-4 Ar-6 Ar-3 Ar-3 Ar-5 Ar-3Ar-3 Ar-3 Ar-5 Ar-4 Ar-3 Ar-3 Ar-5 Ar-5 Ar-3 Ar-3 Ar-5 Ar-6 Ar-3 Ar-3Ar-6 Ar-3 Ar-3 Ar-3 Ar-6 Ar-4 Ar-3 Ar-3 Ar-6 Ar-5 Ar-3 Ar-3 Ar-6 Ar-6Ar-3 Ar-4 Ar-1 Ar-4 Ar-3 Ar-4 Ar-1 Ar-5 Ar-3 Ar-4 Ar-1 Ar-6 Ar-3 Ar-4Ar-2 Ar-4 Ar-3 Ar-4 Ar-2 Ar-5 Ar-3 Ar-4 Ar-2 Ar-6 Ar-3 Ar-4 Ar-3 Ar-4Ar-3 Ar-4 Ar-3 Ar-5 Ar-3 Ar-4 Ar-3 Ar-6 Ar-3 Ar-4 Ar-4 Ar-3 Ar-3 Ar-4Ar-4 Ar-4 Ar-3 Ar-4 Ar-4 Ar-5 Ar-3 Ar-4 Ar-4 Ar-6 Ar-3 Ar-4 Ar-5 Ar-3Ar-3 Ar-4 Ar-5 Ar-4 Ar-3 Ar-4 Ar-5 Ar-5 Ar-3 Ar-4 Ar-5 Ar-6 Ar-3 Ar-4Ar-6 Ar-3 Ar-3 Ar-4 Ar-6 Ar-4 Ar-3 Ar-4 Ar-6 Ar-5 Ar-3 Ar-4 Ar-6 Ar-6Ar-3 Ar-5 Ar-1 Ar-4 Ar-3 Ar-5 Ar-1 Ar-5 Ar-3 Ar-5 Ar-1 Ar-6 Ar-3 Ar-5Ar-2 Ar-4 Ar-3 Ar-5 Ar-2 Ar-5 Ar-3 Ar-5 Ar-2 Ar-6 Ar-3 Ar-5 Ar-3 Ar-4Ar-3 Ar-5 Ar-3 Ar-5 Ar-3 Ar-5 Ar-3 Ar-6 Ar-3 Ar-5 Ar-4 Ar-4 Ar-3 Ar-5Ar-4 Ar-5 Ar-3 Ar-5 Ar-4 Ar-6 Ar-3 Ar-5 Ar-5 Ar-3 Ar-3 Ar-5 Ar-5 Ar-4Ar-3 Ar-5 Ar-5 Ar-5 Ar-3 Ar-5 Ar-5 Ar-6 Ar-3 Ar-5 Ar-6 Ar-3 Ar-3 Ar-5Ar-6 Ar-4 Ar-3 Ar-5 Ar-6 Ar-5 Ar-3 Ar-5 Ar-6 Ar-6 Ar-3 Ar-6 Ar-1 Ar-4Ar-3 Ar-6 Ar-1 Ar-5 Ar-3 Ar-6 Ar-1 Ar-6 Ar-3 Ar-6 Ar-2 Ar-4 Ar-3 Ar-6Ar-2 Ar-5 Ar-3 Ar-6 Ar-2 Ar-6

TABLE 1-9 R1 R3 R4 R6 Ar-3 Ar-6 Ar-3 Ar-4 Ar-3 Ar-6 Ar-3 Ar-5 Ar-3 Ar-6Ar-3 Ar-6 Ar-3 Ar-6 Ar-4 Ar-4 Ar-3 Ar-6 Ar-4 Ar-5 Ar-3 Ar-6 Ar-4 Ar-6Ar-3 Ar-6 Ar-5 Ar-4 Ar-3 Ar-6 Ar-5 Ar-5 Ar-3 Ar-6 Ar-5 Ar-6 Ar-3 Ar-6Ar-6 Ar-3 Ar-3 Ar-6 Ar-6 Ar-4 Ar-3 Ar-6 Ar-6 Ar-5 Ar-3 Ar-6 Ar-6 Ar-6Ar-4 Ar-1 Ar-1 Ar-4 Ar-4 Ar-1 Ar-1 Ar-5 Ar-4 Ar-1 Ar-1 Ar-6 Ar-4 Ar-1Ar-2 Ar-4 Ar-4 Ar-1 Ar-2 Ar-5 Ar-4 Ar-1 Ar-2 Ar-6 Ar-4 Ar-1 Ar-3 Ar-4Ar-4 Ar-1 Ar-3 Ar-5 Ar-4 Ar-1 Ar-3 Ar-6 Ar-4 Ar-1 Ar-4 Ar-4 Ar-4 Ar-1Ar-4 Ar-5 Ar-4 Ar-1 Ar-4 Ar-6 Ar-4 Ar-1 Ar-5 Ar-4 Ar-4 Ar-1 Ar-5 Ar-5Ar-4 Ar-1 Ar-5 Ar-6 Ar-4 Ar-1 Ar-6 Ar-4 Ar-4 Ar-1 Ar-6 Ar-5 Ar-4 Ar-1Ar-6 Ar-6 Ar-4 Ar-2 Ar-1 Ar-5 Ar-4 Ar-2 Ar-1 Ar-6 Ar-4 Ar-2 Ar-2 Ar-4Ar-4 Ar-2 Ar-2 Ar-5 Ar-4 Ar-2 Ar-2 Ar-6 Ar-4 Ar-2 Ar-3 Ar-4 Ar-4 Ar-2Ar-3 Ar-5 Ar-4 Ar-2 Ar-3 Ar-6 Ar-4 Ar-2 Ar-4 Ar-4 Ar-4 Ar-2 Ar-4 Ar-5Ar-4 Ar-2 Ar-4 Ar-6 Ar-4 Ar-2 Ar-5 Ar-4 Ar-4 Ar-2 Ar-5 Ar-5 Ar-4 Ar-2Ar-5 Ar-6 Ar-4 Ar-2 Ar-6 Ar-4 Ar-4 Ar-2 Ar-6 Ar-5 Ar-4 Ar-2 Ar-6 Ar-6Ar-4 Ar-3 Ar-1 Ar-5 Ar-4 Ar-3 Ar-1 Ar-6 Ar-4 Ar-3 Ar-2 Ar-5 Ar-4 Ar-3Ar-2 Ar-6 Ar-4 Ar-3 Ar-3 Ar-4 Ar-4 Ar-3 Ar-3 Ar-5 Ar-4 Ar-3 Ar-3 Ar-6Ar-4 Ar-3 Ar-4 Ar-4 Ar-4 Ar-3 Ar-4 Ar-5 Ar-4 Ar-3 Ar-4 Ar-6 Ar-4 Ar-3Ar-5 Ar-4 Ar-4 Ar-3 Ar-5 Ar-5 Ar-4 Ar-3 Ar-5 Ar-6

TABLE 1-10 R1 R3 R4 R6 Ar-4 Ar-3 Ar-6 Ar-4 Ar-4 Ar-3 Ar-6 Ar-5 Ar-4 Ar-3Ar-6 Ar-6 Ar-4 Ar-4 Ar-1 Ar-5 Ar-4 Ar-4 Ar-1 Ar-6 Ar-4 Ar-4 Ar-2 Ar-5Ar-4 Ar-4 Ar-2 Ar-6 Ar-4 Ar-4 Ar-3 Ar-5 Ar-4 Ar-4 Ar-3 Ar-6 Ar-4 Ar-4Ar-4 Ar-4 Ar-4 Ar-4 Ar-4 Ar-5 Ar-4 Ar-4 Ar-4 Ar-6 Ar-4 Ar-4 Ar-5 Ar-4Ar-4 Ar-4 Ar-5 Ar-5 Ar-4 Ar-4 Ar-5 Ar-6 Ar-4 Ar-4 Ar-6 Ar-4 Ar-4 Ar-4Ar-6 Ar-5 Ar-4 Ar-4 Ar-6 Ar-6 Ar-4 Ar-5 Ar-1 Ar-5 Ar-4 Ar-5 Ar-1 Ar-6Ar-4 Ar-5 Ar-2 Ar-5 Ar-4 Ar-5 Ar-2 Ar-6 Ar-4 Ar-5 Ar-3 Ar-5 Ar-4 Ar-5Ar-3 Ar-6 Ar-4 Ar-5 Ar-4 Ar-5 Ar-4 Ar-5 Ar-4 Ar-6 Ar-4 Ar-5 Ar-5 Ar-4Ar-4 Ar-5 Ar-5 Ar-5 Ar-4 Ar-5 Ar-5 Ar-6 Ar-4 Ar-5 Ar-6 Ar-4 Ar-4 Ar-5Ar-6 Ar-5 Ar-4 Ar-5 Ar-6 Ar-6 Ar-4 Ar-6 Ar-1 Ar-5 Ar-4 Ar-6 Ar-1 Ar-6Ar-4 Ar-6 Ar-2 Ar-5 Ar-4 Ar-6 Ar-2 Ar-6 Ar-4 Ar-6 Ar-3 Ar-5 Ar-4 Ar-6Ar-3 Ar-6 Ar-4 Ar-6 Ar-4 Ar-5 Ar-4 Ar-6 Ar-4 Ar-6 Ar-4 Ar-6 Ar-5 Ar-5Ar-4 Ar-6 Ar-5 Ar-6 Ar-4 Ar-6 Ar-6 Ar-4 Ar-4 Ar-6 Ar-6 Ar-5 Ar-4 Ar-6Ar-6 Ar-6 Ar-5 Ar-1 Ar-1 Ar-5 Ar-5 Ar-1 Ar-1 Ar-6 Ar-5 Ar-1 Ar-2 Ar-5Ar-5 Ar-1 Ar-2 Ar-6 Ar-5 Ar-1 Ar-3 Ar-5 Ar-5 Ar-1 Ar-3 Ar-6 Ar-5 Ar-1Ar-4 Ar-5 Ar-5 Ar-1 Ar-4 Ar-6 Ar-5 Ar-1 Ar-5 Ar-5 Ar-5 Ar-1 Ar-5 Ar-6Ar-5 Ar-1 Ar-6 Ar-5 Ar-5 Ar-1 Ar-6 Ar-6 Ar-5 Ar-2 Ar-1 Ar-6 Ar-5 Ar-2Ar-2 Ar-5 Ar-5 Ar-2 Ar-2 Ar-6 Ar-5 Ar-2 Ar-3 Ar-5 Ar-5 Ar-2 Ar-3 Ar-6

TABLE 1-11 R1 R3 R4 R6 Ar-5 Ar-2 Ar-4 Ar-5 Ar-5 Ar-2 Ar-4 Ar-6 Ar-5 Ar-2Ar-5 Ar-5 Ar-5 Ar-2 Ar-5 Ar-6 Ar-5 Ar-2 Ar-6 Ar-5 Ar-5 Ar-2 Ar-6 Ar-6Ar-5 Ar-3 Ar-1 Ar-6 Ar-5 Ar-3 Ar-2 Ar-6 Ar-5 Ar-3 Ar-3 Ar-5 Ar-5 Ar-3Ar-3 Ar-6 Ar-5 Ar-3 Ar-4 Ar-5 Ar-5 Ar-3 Ar-4 Ar-6 Ar-5 Ar-3 Ar-5 Ar-5Ar-5 Ar-3 Ar-5 Ar-6 Ar-5 Ar-3 Ar-6 Ar-5 Ar-5 Ar-3 Ar-6 Ar-6 Ar-5 Ar-4Ar-1 Ar-6 Ar-5 Ar-4 Ar-2 Ar-6 Ar-5 Ar-4 Ar-3 Ar-6 Ar-5 Ar-4 Ar-4 Ar-5Ar-5 Ar-4 Ar-4 Ar-6 Ar-5 Ar-4 Ar-5 Ar-5 Ar-5 Ar-4 Ar-5 Ar-6 Ar-5 Ar-4Ar-6 Ar-5 Ar-5 Ar-4 Ar-6 Ar-6 Ar-5 Ar-5 Ar-1 Ar-6 Ar-5 Ar-5 Ar-2 Ar-6Ar-5 Ar-5 Ar-3 Ar-6 Ar-5 Ar-5 Ar-4 Ar-6 Ar-5 Ar-5 Ar-5 Ar-5 Ar-5 Ar-5Ar-5 Ar-6 Ar-5 Ar-5 Ar-6 Ar-5 Ar-5 Ar-5 Ar-6 Ar-6 Ar-5 Ar-6 Ar-1 Ar-6Ar-5 Ar-6 Ar-2 Ar-6 Ar-5 Ar-6 Ar-3 Ar-6 Ar-5 Ar-6 Ar-4 Ar-6 Ar-5 Ar-6Ar-5 Ar-6 Ar-5 Ar-6 Ar-6 Ar-5 Ar-5 Ar-6 Ar-6 Ar-6 Ar-6 Ar-1 Ar-1 Ar-6Ar-6 Ar-1 Ar-2 Ar-6 Ar-6 Ar-1 Ar-3 Ar-6 Ar-6 Ar-1 Ar-4 Ar-6 Ar-6 Ar-1Ar-5 Ar-6 Ar-6 Ar-1 Ar-6 Ar-6 Ar-6 Ar-2 Ar-2 Ar-6 Ar-6 Ar-2 Ar-3 Ar-6Ar-6 Ar-2 Ar-4 Ar-6 Ar-6 Ar-2 Ar-5 Ar-6 Ar-6 Ar-2 Ar-6 Ar-6 Ar-6 Ar-3Ar-3 Ar-6 Ar-6 Ar-3 Ar-4 Ar-6 Ar-6 Ar-3 Ar-5 Ar-6 Ar-6 Ar-3 Ar-6 Ar-6Ar-6 Ar-4 Ar-4 Ar-6 Ar-6 Ar-4 Ar-5 Ar-6 Ar-6 Ar-4 Ar-6 Ar-6 Ar-6 Ar-5Ar-5 Ar-6 Ar-6 Ar-5 Ar-6 Ar-6 Ar-6 Ar-6 Ar-6 Ar-6

R² and R⁵ are each preferably any of hydrogen, an alkyl group, acarbonyl group, an oxycarbonyl group, and an aryl group. Among them,hydrogen and an alkyl group are preferred in view of thermal stability,and hydrogen is more preferred in view of the easiness of obtaining anarrow full width at half maximum in an emission spectrum.

R⁸ and R⁹ are each preferably an alkyl group, an aryl group, aheteroaryl group, fluorine, a fluorine-containing alkyl group, afluorine-containing heteroaryl group, or a fluorine-containing arylgroup. In particular, because of being stable against excitation lightand the capability of obtaining higher emission quantum yield, R⁸ and R⁹are each more preferably fluorine or a fluorine-containing aryl group.In addition, R⁸ and R⁹ are each still more preferably fluorine in viewof the easiness of synthesis.

The fluorine-containing aryl group is an aryl group containing fluorine;examples thereof include a fluorophenyl group, a trifluoromethylphenylgroup, and pentafluorophenyl group. The fluorine-containing heteroarylgroup is a heteroaryl group containing fluorine; examples thereofinclude a fluoropyridyl group, a trifluoromethylpyridyl group, andtrifluoropyridyl group. The fluorine-containing alkyl group is an alkylgroup containing fluorine; examples thereof include a trifluoromethylgroup and a pentafluoroethyl group.

In General Formula (1), X is preferably C—R⁷ in view of photostability.When X is C—R⁷, the substituent R⁷ has a great influence on thedurability of the compound represented by General Formula (1), that is,a temporal reduction in the emission intensity of this compound.Specifically, when R⁷ is hydrogen, the reactivity of this part is high,and this part and water and oxygen in the air easily react with eachother. This phenomenon causes the decomposition of the compoundrepresented by General Formula (1). When R⁷ is a substituent having alarge degree of freedom of the motion of a molecular chain such as analkyl group, although the reactivity indeed reduces, the compoundsflocculate with the lapse of time in the color conversion sheet,resulting in a reduction in emission intensity caused by concentrationquenching. Thus, R⁷ is preferably a group that is rigid, is small in thedegree of freedom of motion, and is difficult to cause flocculation, andspecifically preferably any of a substituted or unsubstituted aryl groupand a substituted or unsubstituted heteroaryl group.

In view of giving higher emission quantum yield, being more resistant tothermal decomposition, and photostability, X is preferably C—R⁷ in whichR⁷ is a substituted or unsubstituted aryl group. In view of notimpairing emission wavelength, the aryl group is preferably a phenylgroup, a biphenyl group, a terphenyl group, a naphthyl group, afluorenyl group, a phenanthryl group, or an anthracenyl group.

In addition, to increase the photostability of the compound representedby General Formula (1), the twist of the carbon-carbon bond between R⁷and the pyrromethene skeleton is required to be appropriately reduced,because an excessively large twist causes a reduction in photostability,such as an increase in reactivity against the excitation light. Giventhese circumstances, R⁷ is preferably a substituted or unsubstitutedphenyl group, a substituted or unsubstituted biphenyl group, asubstituted or unsubstituted terphenyl group, or a substituted orunsubstituted naphthyl group, more preferably a substituted orunsubstituted phenyl group, a substituted or unsubstituted biphenylgroup, or a substituted or unsubstituted terphenyl group, andparticularly preferably a substituted or unsubstituted phenyl group.

R⁷ is preferably a moderately bulky substituent. R⁷ has bulkiness tosome extent, whereby the flocculation of molecules can be prevented.Consequently, the emission efficiency and durability of the compoundrepresented by General Formula (1) further improve.

A further preferred example of the bulky substituent is the structure ofR⁷ represented by the following General Formula (2).

In General Formula (2), r is selected from the group consisting ofhydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, analkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxy group,a thiol group, an alkoxy group, an alkylthio group, an aryl ether group,an aryl thioether group, an aryl group, a heteroaryl group, halogen, acyano group, an aldehyde group, a carbonyl group, a carboxy group, anoxycarbonyl group, a carbamoyl group, an amino group, a nitro group, asilyl group, a siloxanyl group, a boryl group, and a phosphine oxidegroup. The symbol k is an integer of 1 to 3. When k is 2 or more, rs maybe the same as or different from each other.

In view of the capability of giving higher emission quantum yield, r ispreferably a substituted or unsubstituted aryl group. Preferred examplesof the aryl group include a phenyl group and a naphthyl group inparticular. When r is an aryl group, k in General Formula (2) ispreferably 1 or 2 and more preferably 2 in view of preventing theflocculation of molecules. In addition, when k is 2 or more, at leastone of rs is preferably substituted by an alkyl group. Particularlypreferred examples of the alkyl group in this case include a methylgroup, an ethyl group, and a tert-butyl group in view of thermalstability.

In view of controlling fluorescence wavelength and absorption wavelengthand increasing compatibility with the solvent, r is preferably asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedalkoxy group, or halogen and more preferably a methyl group, an ethylgroup, a tert-butyl group, or a methoxy group. In view ofdispersibility, r is particularly preferably a tert-butyl group or amethoxy group. The fact that r is a tert-butyl group or a methoxy groupis more effective for the prevention of quenching caused by theflocculation of molecules.

As another mode of the compound represented by General Formula (1), atleast one of R¹ to R⁷ is preferably an electron withdrawing group. Inparticular, preferred is (1) at least one of R¹ to R⁶ being an electronwithdrawing group, (2) R⁷ being an electron withdrawing group, or (3) atleast one of R¹ to R⁶ being an electron withdrawing group and R⁷ beingan electron withdrawing group. The electron withdrawing group is thusintroduced to the pyrromethene skeleton of the compound, whereby theelectron density of the pyrromethene skeleton can be greatly reduced.With this reduction in electron density, the stability of the compoundagainst oxygen further improves, and consequently, the durability of thecompound can be further improved.

The electron withdrawing group is called also an electron acceptinggroup and is an atomic group that attracts an electron from asubstituted atomic group by the inductive effect and/or the resonanceeffect in the organic electron theory. Examples of the electronwithdrawing group include ones having a positive value as a substituentconstant (σp (para)) of Hammett's Rule. The substituent constant (σp(para)) of Hammett's Rule can be cited from Kagaku Binran Kiso-HenRevised 5th Edition (II, p. 380). Although the phenyl group has anexample taking a positive value as in the above, the electronwithdrawing group does not include the phenyl group in the presentinvention.

Examples of the electron withdrawing group include —F (σp: +0.06), —Cl(σp: +0.23), —Br (σp: +0.23), —I (σp: +0.18), —CO₂R¹² (σp: +0.45 whenR¹² is an ethyl group), —CONH₂ (σp: +0.38), —COR¹² (σp: +0.49 when R¹²is a methyl group), —CF₃ (σp: +0.50), —SO₂R¹² (σp: +0.69 when R¹² is amethyl group), and —NO₂ (σp: +0.81). R¹²s each independently represent ahydrogen atom, a substituted or unsubstituted aromatic hydrocarbon groupwith a ring-forming carbon number of 6 o 30, a substituted orunsubstituted heterocyclic group with a ring-forming carbon number of 5o 30, a substituted or unsubstituted C₁₋₃₀ alkyl group, or a substitutedor unsubstituted C₁₋₃₀ cycloalkyl group. Specific examples of thesegroups include examples similar to those described above.

Preferred examples of the electron withdrawing group include fluorine, afluorine-containing aryl group, a fluorine-containing heteroaryl group,a fluorine-containing alkyl group, a substituted or unsubstituted acylgroup, a substituted or unsubstituted ester group, a substituted orunsubstituted amide group, a substituted or unsubstituted sulfonylgroup, and a cyano group; this is because they are resistant to chemicaldecomposition.

More preferred examples of the electron withdrawing group include afluorine-containing alkyl group, a fluorine-containing aryl group, asubstituted or unsubstituted acyl group, a substituted or unsubstitutedester group, and a cyano group; this is because they preventconcentration quenching, leading to an effect of improving emissionquantum yield. A particularly preferred electron withdrawing group is asubstituted or unsubstituted ester group.

One preferred example of the compound represented by General Formula (1)suitably used as the organic light-emitting material (a), the organiclight-emitting material (a′), and the organic light-emitting material(d) is a case in which all R¹, R³, R⁴, and R⁶ may be the same as ordifferent from each other and are substituted or unsubstituted alkylgroups, X is C—R⁷, and R⁷ is the group represented by General Formula(2). In this case, R⁷ is particularly preferably the group representedby General Formula (2) in which r is contained as a substituted orunsubstituted phenyl group.

Another preferred example of the compound represented by General Formula(1) suitably used as the organic light-emitting material (b), theorganic light-emitting material (b′), and the organic light-emittingmaterial (c) is a case in which all R¹, R³, R⁴, and R⁶ may be the sameas or different from each other and are selected from Ar-1 to Ar-6described above, X is C—R⁷, and R⁷ is the group represented by GeneralFormula (2). In this case, R⁷ is more preferably the group representedby General Formula (2) in which r is contained as a tert-butyl group ora methoxy group and particularly preferably the group represented byGeneral Formula (2) in which r is contained as a methoxy group.

The following shows examples of the compound represented by GeneralFormula (1); this compound is not limited to these examples.

The compound represented by General Formula (1) can be synthesized by amethod described in Japanese Translation of PCT Application No.H08-509471 and Japanese Patent Application Laid-open No. 2000-208262,for example. That is, a pyrromethene compound and a metal salt arereacted with each other in the presence of a base to obtain a targetpyrromethene-based metal complex.

For the synthesis of a pyrromethene-boron fluoride complex, methodsdescribed in J. Org. Chem., vol. 64, No. 21, pp. 7813-7819 (1999),Angew. Chem., Int. Ed. Engl., vol. 36, pp. 1333-1335 (1997), and thelike are referred to, whereby the compound represented by GeneralFormula (1) can be synthesized. Examples of the methods include a methodthat heats a compound represented by the following General Formula (3)and a compound represented by the following General Formula (4) in1,2-dichloroethane in the presence of phosphoryl chloride and reactsthem with a compound represented by the following General Formula (5) in1,2-dichloroethane in the presence of triethylamine, thereby obtainingthe compound represented by General Formula (1). However, the presentinvention is not limited to this method. R¹ to R⁹ are similar to thosedescribed above. J represents halogen.

In addition, in introducing an aryl group or a heteroaryl group, thereis a method that forms a carbon-carbon bond using a coupling reactionbetween a halogenated derivative and boronic acid or an esterifiedboronic acid derivative; the present invention is not limited to thismethod. Similarly, in introducing an amino group or a carbazolyl group,there is a method that forms a carbon-nitrogen bond using a couplingreaction between a halogenated derivative and an amine or a carbazolederivate in the presence of a metallic catalyst such as palladium, forexample; the present invention is not limited to this method.

The color conversion sheet according to the embodiment of the presentinvention can contain other compounds as appropriate as needed, inaddition to the compound represented by General Formula (1). To furtherincrease energy transfer efficiency to the compound represented byGeneral Formula (1) from the excitation light, assist dopants such asrubrene may be contained, for example. When any light emission colorother than the light emission color of the compound represented byGeneral Formula (1) is desired to be added, the color conversioncomposition can add desired organic light-emitting materials includingorganic light-emitting materials such as coumarin-based dyes andrhodamine-based dyes. Other than these organic light-emitting materials,known light-emitting materials such as inorganic fluorescent bodies,fluorescent pigments, fluorescent dyes, and quantum dots can be added incombination.

The following shows examples of the organic light-emitting materialother than the compound represented by General Formula (1); the presentinvention is not limited particularly to these examples.

In the color conversion sheet according to the embodiment of the presentinvention, the content of the organic light-emitting material in each ofthe layer (A) and the layer (B), which depends on the molar extinctioncoefficient, the emission quantum yield, and the absorption intensity atan excitation wavelength of the compound and the thickness and thetransmittance of a sheet to be prepared, is usually 1.0×10⁻⁴ part byweight to 30 parts by weight relative to 100 parts by weight of thebinder resin. In particular, the content of the organic light-emittingmaterial in each of the layers is further preferably 1.0×10⁻³ part byweight to 10 parts by weight and particularly preferably 5.0×10⁻³ partby weight to 5 parts by weight relative to 100 parts by weight of thebinder resin.

In the color conversion sheet according to the embodiment of the presentinvention, part of the green light emission is converted into the redlight emission, and a content w_(a) of an organic light-emittingmaterial (a) in the layer (A) and a content w_(b) of an organiclight-emitting material (b) in the layer (B) preferably have a relationof w_(a)≥w_(b); the ratio between the content w_(a) and the contentw_(b) is w_(a):w_(b)=1000:1 to 1:1, further preferably 500:1 to 2:1, andparticularly preferably 200:1 to 3:1, where the content w_(a) and thecontent w_(b) are percentages by weight relative to the weight of therespective binder resins in the respective layers of the layer (A) andthe layer (B).

When the layer (A) and the layer (B) further contain some organiclight-emitting materials other than the organic light-emitting material(a) and the organic light-emitting material (b), the content of anadditional organic light-emitting material is preferably an amount thatdoes not have an excessive influence on the light emission of theorganic light-emitting material (a) and the organic light-emittingmaterial (b).

When the layer (A) contains the organic light-emitting material (a′)other than the organic light-emitting material (a), for example, thecontent w_(a) of the organic light-emitting material (a) in the layer(A) and a content w_(a)′ of the organic light-emitting material (a′) inthe layer (A) preferably have a relation of w_(a)≥w_(a)′ because of nothaving an excessive influence on the light emission of the organiclight-emitting material (a). The ratio between the content w_(a) and thecontent w_(a)′ is w_(a):w_(a)′=1000:1 to 1:1, further preferably 500:1to 2:1, and particularly preferably 200:1 to 3:1, where the contentw_(a)′ is a percentage by weight relative to the weight of binder resinin the layer (A).

When the layer (A) contains the organic light-emitting material (c)other than the organic light-emitting material (a), the content w_(a) ofthe organic light-emitting material (a) in the layer (A) and a contentwe of the organic light-emitting material (c) in the layer (A)preferably have a relation of w_(a)≥w_(c) because of not having anexcessive influence on the light emission of the organic light-emittingmaterial (a). The ratio between the content w_(a) and the content we isw_(a):w_(c)=1000:1 to 1:1, further preferably 500:1 to 2:1, andparticularly preferably 200:1 to 3:1, where the content w_(c) is apercentage by weight relative to the weight of the binder resin in thelayer (A).

The content w_(a) of the organic light-emitting material (a) in thelayer (A), the content w_(c) of the organic light-emitting material (c)in the layer (A), and the content w_(b) of the organic light-emittingmaterial (b) in the layer (B) preferably have a relation ofw_(a)≥w_(b)≥w_(c) because of not having an excessive influence on thelight emission of the organic light-emitting material (a) and theorganic light-emitting material (b).

When the layer (B) contains the organic light-emitting material (b′)other than the organic light-emitting material (b), the content w_(b) ofthe organic light-emitting material (b) in the layer (B) and a contentw_(b)′ of the organic light-emitting material (b′) in the layer (B)preferably have a relation of w_(b)≥w_(b)′ because of not having anexcessive influence on the light emission of the organic light-emittingmaterial (b). The ratio between the content w_(b) and the content w_(b)′is w_(b):w_(b)′=1000:1 to 1:1, further preferably 500:1 to 2:1, andparticularly preferably 200:1 to 3:1, where the content w_(b)′ is apercentage by weight relative to the weight of the binder resin in thelayer (B).

When the layer (B) contains the organic light-emitting material (d)other than the organic light-emitting material (b), the content w_(a) ofthe organic light-emitting material (a) in the layer (A) and a contentw_(d) of the organic light-emitting material (d) in the layer (B)preferably have a relation of w_(a)≥w_(d) because of not having anexcessive influence on the light emission of the organic light-emittingmaterial (a). The ratio between the content w_(a) and the content w_(d)is w_(a):w_(d)=1000:1 to 1:1, further preferably 500:1 to 2:1, andparticularly preferably 200:1 to 3:1, where the content w_(d) is apercentage by weight relative to the weight of the binder resin in thelayer (B).

(Binder Resin)

In the color conversion composition and the color conversion sheetaccording to the embodiment of the present invention, materialsexcellent in formability, transparency, heat resistance, and the likeare suitably used for the binder resin. Examples of the binder resininclude known ones such as photocurable resist materials having areactive vinyl group such as acrylic acid-based, methacrylic acid-based,vinyl polycinnamate-based, or cyclized rubber-based one, epoxy resins,silicone resins (including organopolysiloxane cured objects(cross-linked objects) such as silicone rubbers and silicone gels), urearesins, fluorine resins, polycarbonate resins, acrylic resins, urethaneresins, melamine resins, polyvinyl resins, polyamide resins, phenolresins, polyvinyl alcohol resins, polyvinyl butyral resins, celluloseresins, aliphatic ester resins, aromatic ester resins, aliphaticpolyolefin resins, and aromatic polyolefin resins. For the binder resin,a mixture or copolymer of these resins may be used. These resins aredesigned as appropriate, whereby the binder resin useful for the colorconversion sheet according to the embodiment of the present invention isobtained.

Among these resins, in view of transparency, heat resistance, and thelike, suitably used are epoxy resins, silicone resins, acrylic resins,polyester resins, and mixtures thereof. Because of the easiness of theprocess of being made into film, thermosetting resins and photocurableresins are also suitably used.

A combination of the organic light-emitting material and the binderresin in each of the layer (A) and the layer (B) is optimized, wherebythe emission peak wavelength of the organic light-emitting material canbe shifted to a desired wavelength, and the color gamut can be expanded.For this purpose, the binder resin contained in the layer (A) and thebinder resin contained in the layer (B) are preferably different fromeach other. By doing so, the organic light-emitting material (a) thatconverts the blue light into the green light and the organiclight-emitting material (b) that converts the blue light and the greenlight into the red light are dispersed in different binder resins toenable the respective emission peak wavelengths of the organiclight-emitting material (a) and the organic light-emitting material (b)to be individually adjusted to respective optimum peak wavelengths. Thatthe two binder resins are different from each other refers to that thecompositions of the resins are different from each other.

In the color conversion sheet according to the embodiment of the presentinvention, in obtaining favorable white light, the emission peakwavelength from the layer (A) is preferably observed in a region of 500nm or more and 580 nm or less. In improving color reproducibility, theemission peak wavelength from the layer (A) is more preferably 510 nm ormore and 550 nm or less, further preferably 515 nm or more and 540 nm orless, and particularly preferably 520 nm or more and 535 nm or less.

In the color conversion sheet according to the embodiment of the presentinvention, in obtaining favorable white light, the emission peakwavelength from the layer (B) is preferably observed in a region of 580nm or more and 750 nm or less. In improving color reproducibility, theemission peak wavelength from the layer (B) is more preferably 610 nm ormore and 700 nm or less, further preferably 620 nm or more and 680 nm orless, and particularly preferably 630 nm or more and 660 nm or less.

An SP value as a solubility parameter of the binder resin and theemission peak wavelength of the organic light-emitting material havestrong relation. In a binder resin having a large SP value, interactionbetween the binder resin and the organic light-emitting materialstabilizes the excited state of the organic light-emitting material. Forthis reason, the emission peak wavelength of this organic light-emittingmaterial shifts to a longer wavelength side than in a binder resinhaving a smaller SP value. Consequently, the organic light-emittingmaterial is dispersed in the binder resin having an optimum SP value,whereby the emission peak wavelength of the organic light-emittingmaterial can be optimized. Optimizing the peak wavelength of the lightemission of an organic light-emitting material having high color purityenables the concentration of a color filter to be low and enables adisplay to have higher luminance, for example, in cases where theorganic light-emitting material is incorporated in the light source ofthe display as below-mentioned.

In the color conversion sheet according to the embodiment of the presentinvention, SP_(A)>SP_(B) where an SP value of the binder resin containedin the layer (A) is SP_(A) (cal/cm³)^(0.5) and the SP value of thebinder resin contained in the layer (B) is SP_(B) (cal/cm³)^(0.5). Inthis case, the difference between the emission peak wavelengths of thegreen light and the red light in the layer (A) and the layer (B),respectively, is smaller than a case in which the organic light-emittingmaterials are dispersed in the same binder resin. As a result, lightconverted into light having a large visibility region is condensed, andthus improves the luminance.

In particular, preferably SP_(B)≤10.0. In this case, shift to a longerwavelength of the emission peak wavelength of the red light in the layer(B) is reduced, and consequently, the difference between the emissionpeak wavelengths of the green light and the red light in the layer (A)and the layer (B), respectively, is smaller, which is thus preferred. Inview of enhancing the effect, more preferably SP_(B)≤9.8, furtherpreferably SP_(B)≤9.7, and particularly preferably SP_(B)≤9.6.

The lower limit value of SP_(B) is not limited to a particular value;the binder resin having SP_(B)≥7.0 is favorable in the dispersibility ofthe organic light-emitting material and can be thus suitably used. Inview of enhancing the effect, more preferably SP_(B)≥8.0, furtherpreferably SP_(B)≥8.5, and particularly preferably SP_(B)≥9.0.

Particularly preferably, 9.0≤SP_(B)≤10.0. In cases where SP_(B) is inthis range, an effect of improving luminance significantly can beobtained without impairing the dispersibility of the organiclight-emitting material.

In addition, preferably SP_(A)≥10.0. In this case, the emission peakwavelength of the green light in the layer (A) shifts to a longerwavelength by a larger amount, and consequently, the layer (A) can emitgreen light, which is in a wavelength region having large visibility. Inview of enhancing the effect, more preferably SP_(A)≥10.2, furtherpreferably SP_(A)≥10.4, and particularly preferably SP_(A)≥10.6.

The upper limit value of SP_(A) is not limited to a particular value;the binder resin having SP_(A)≤15.0 is favorable in the dispersibilityof the organic light-emitting material and can be thus suitably used. Inview of enhancing the effect, more preferably SP_(A)≤14.0, furtherpreferably SP_(A)≤13.0, and particularly preferably SP_(A)≤12.0.

The solubility parameter (SP value) is a value calculated from the typeand proportion of monomers contained in a resin using Fedors' method ofestimation described in Poly. Eng. Sci., vol. 14, No. 2, pp. 147-154(1974) and the like, which is generally used. For a mixture of aplurality of resins, the value can be calculated by a similar method.The SP value of polymethyl methacrylate can be calculated to be 9.7(cal/cm³)^(0.5), the SP value of polyethylene terephthalate (PET) can becalculated to be 10.8 (cal/cm³)^(0.5), and the SP value of bisphenol Aepoxy resin can be calculated to be 10.9 (cal/cm³)^(0.5), for example.

The binder resins in the layer (A) and the layer (B) are not limited toparticular resins; Table 2 lists the type of binder resins that can besuitably used for the layer (A) and binder resins that can be suitablyused for the layer (B) and representative SP values of the respectiveresins. The binder resins in the layer (A) and the layer (B) arepreferably any combination of the resins listed in Table 2, for example.

TABLE 2 Layer (A) (SP Value*) Layer (B) (SP Value*) Acrylic Resin(9.3-9.9) Acrylic Resin (9.3-9.9) Epoxy Resin (10.9) Epoxy Resin (10.9)Polyester Resin (10.7) Polyester Resin (10.7) Urethane Resin (10)Urethane Resin (10) Vinyl Acetate Resin (9.4) Vinyl Acetate Resin (9.4)Polyvinyl Alcohol (12.6) Vinyl Chloride Resin (9.7) Vinylidene ChlorideResin (12.2) Silicone Resin (7.3-7.6) Polyamide Resin (13.6) FluorineResin (6.2) Acrylonitrile Resin (14.8) Styrene-butadiene Rubber(8.3-8.6) Polystyrene (9.6) Polystyrene (9.6) Hydrogenated Polystyrene(8.8) Cycloolefin (8.9) *unit: (cal/cm³)^(0.5)

As the binder resin in the layer (B), olefinic resins, acrylic resins,epoxy resins, polyester resins, vinyl acetate resins, silicone resins,and polystyrene resins can be suitably used among others, because theseresins have high transparency in the visible range. Acrylic resins andpolyester resins are more preferable, and acrylic resins areparticularly preferable.

As the binder resin in the layer (A), acrylic resins, epoxy resins,polyester resins, and vinyl acetate resins can be suitably used, becausethese resins have high transparency in the visible range. Acrylic resinsand polyester resins are more preferable, and polyester resins areparticularly preferable.

(Other Additives)

The color conversion composition and the color conversion sheetaccording to the embodiment of the present invention can contain otheradditives such as antioxidants, processing-and-thermal stabilizers,lightfast stabilizers such as ultraviolet absorbers, dispersants andleveling agents for stabilizing coatings, plasticizers, cross-linkingagents such as epoxy compounds, curing agents such as amines, acidanhydrides, and imidazole, adhesive assistants such as silane couplingagents as a modifier for sheet surface, inorganic particles such assilica particles and silicone fine particles as a color conversionmaterial settling inhibitor, and silane coupling agents, in addition tothe organic light-emitting material (a), the organic light-emittingmaterial (b), and the binder resin.

Examples of the antioxidants include, but are not limited to,phenol-based antioxidants such as 2,6-di-tert-butyl-p-cresol and2,6-di-tert-butyl-4-ethylphenol. These antioxidants may be containedsingly or in combination.

Examples of the processing-and-thermal stabilizers include, but are notlimited to, phosphorous-based stabilizers such as tributyl phosphite,tricyclohexyl phosphite, triethyl phosphine, and diphenylbutylphosphine. These stabilizers may be contained singly or in combination.

Examples of the lightfast stabilizers include, but are not limited to,benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole. Theselightfast stabilizers may be contained singly or in combination.

In view of not hindering the light from the light source and the lightemission of the light-emitting material, these additives are preferablysmall in extinction coefficient in the visible range. Specifically, amolar extinction coefficient e of these additives is preferably 1,000 orless, more preferably 500 or less, further preferably 200 or less, andparticularly preferably 100 or less in the entire wavelength range of400 nm or more and 800 nm or less.

For the lightfast stabilizers, compounds having a role as a singletoxygen quencher can also be suitably used. The singlet oxygen quencheris a material that traps singlet oxygen produced from oxygen moleculesactivated through optical energy and deactivates the singlet oxygen. Thesinglet oxygen quencher coexisting in the color conversion sheet canprevent the light-emitting material from degrading by the singletoxygen.

It is known that the singlet oxygen is produced by the occurrence ofelectron and energy exchange between a triplet excited state of dye suchas rose bengal or methylene blue and an oxygen molecule in the groundstate.

In the color conversion sheet according to an embodiment of the presentinvention, the contained organic light-emitting material is excited bythe excitation light and emits light with a wavelength different fromthat of the excitation light to perform light color conversion. Thisexcitation-emission cycle is repeated, and interaction between producedexcited species and oxygen contained in the color conversion sheetincreases the probability of the singlet oxygen being produced.Consequently, the probability of collision of the organic light-emittingmaterial and the singlet oxygen also increases, and the degradation ofthe organic light-emitting material is likely to proceed.

Organic light-emitting materials are susceptible to the influence of thesinglet oxygen compared with inorganic light-emitting materials. Thecompound represented by General Formula (1) in particular is higher inreactivity with the singlet oxygen than compounds having a condensedaryl ring such as perylene or derivatives thereof and thus receives alarge influence on durability by the singlet oxygen. Given thesecircumstances, the produced singlet oxygen is quickly deactivated by thesinglet oxygen quencher, whereby the durability of the compoundrepresented by General Formula (1) excellent in emission quantum yieldand color purity can be improved.

Examples of the compounds having a role as a singlet oxygen quencherinclude, but are not limited to, specific tertiary amines, catecholderivatives, and nickel compounds. These compounds (lightfaststabilizers) may be contained singly or in combination.

The tertiary amines refer to compounds having a structure in which allthe N—H bonds of ammonia are replaced with N—C bonds. The substituent onthe nitrogen atom is selected from an alkyl group, a cycloalkyl group, aheterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynylgroup, an aryl group, a heteroaryl group, an aldehyde group, a carbonylgroup, a carboxy group, an oxycarbonyl group, a carbamoyl group, and acondensed ring and an aliphatic ring formed between adjacentsubstituents. These substituents may be further substituted by thesubstituents described above.

The substituent on the nitrogen atom of the tertiary amines ispreferably a substituted or unsubstituted alkyl group, a substituted orunsubstituted cycloalkyl group, a substituted or unsubstituted arylgroup, or a substituted or unsubstituted heteroaryl group in view ofphotostability. Among them, more preferred are a substituted orunsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, or a substituted or unsubstituted aryl group.

The aryl group in this case is preferably a phenyl group or a naphthylgroup and more preferably a phenyl group, because it does not hinder thelight from the light source and the light emission of the light-emittingmaterial. An increased number of aryl groups on the nitrogen atom causesconcern about an increase in light absorption in the visible range, andamong the three substituents on the nitrogen atom, the number of thearyl groups is preferably two or less and more preferably one or less.When at least one of the three substituents on the nitrogen atom is asubstituted or unsubstituted alkyl group, the singlet oxygen can betrapped more efficiently, which is thus preferred. In particular, two ormore of the three substituents are preferably substituted orunsubstituted alkyl groups.

Preferred examples of the tertiary amines include, but are not limitedto, triethylamine, 1,4-diazabicyclo[2.2.2]octane, tri-n-butylamine,N,N-diethylaniline, and 2,2,6,6-tetramethylpiperidine.

The catechol derivatives refer to compounds having two or more hydroxygroups on a benzene ring including isomers such as resorcinol andhydroquinone. These compounds can trap the singlet oxygen moreefficiently than phenol derivatives, in which one hydroxy group is onthe benzene ring.

The substituent on the benzene ring of catechol derivatives is selectedfrom hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group,an alkenyl group, a cycloalkenyl group, an alkynyl group, a thiol group,an alkoxy group, an alkylthio group, an aryl ether group, an arylthioether group, an aryl group, a heteroaryl group, halogen, a cyanogroup, an aldehyde group, a carbonyl group, a carboxy group, anoxycarbonyl group, a carbamoyl group, an amino group, a nitro group, asilyl group, a siloxanyl group, a boryl group, a phosphine oxide group,and a condensed ring and an aliphatic ring formed between adjacentsubstituents other than a hydroxy group. These substituents may befurther substituted by the substituents described above.

Among them, preferred are a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group, a substituted orunsubstituted aryl group, a substituted or unsubstituted heteroarylgroup, or halogen in view of photostability, and more preferred are asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedcycloalkyl group, a substituted or unsubstituted aryl group, or halogen.In addition, more preferred are a substituted or unsubstituted alkylgroup, a substituted or unsubstituted cycloalkyl group, or halogenbecause of being less in discoloration after reaction with the singletoxygen quencher. Particularly preferred is a substituted orunsubstituted alkyl group.

As to the position of the hydroxy groups on the benzene ring of catecholderivatives, at least two hydroxy groups are preferably adjacent to eachother. This is because the compound is more resistant to photooxidationthan resorcinol (1,3-substituted) and hydroquinone (1,4-substituted).Also after being oxidized, light absorption in the visible range issmall, and the discoloration of the color conversion sheet can beprevented.

Preferred examples of the catechol derivatives include, but are notlimited to, 4-tert-butylbenzene-1,2-diol and3,5-di-tert-butylbenzene-1,2-diol.

The nickel compounds are compounds containing nickel; examples of thenickel compounds include, but are not limited to, inorganic salts suchas nickel chloride, complexes such as bis(acetylacetonate)nickel, andsalts of organic acids such as nickel carbamate. The organic acids referto organic compounds having a carboxy group, a sulfonyl group, aphenolic hydroxy group, or a thiol group. Among them, in view of beinguniformly dispersed in the color conversion sheet, the nickel compoundsare preferably complexes and salts of organic acids.

Examples of nickel complexes and nickel salts of organic acids suitablyused as the singlet oxygen quencher include, but are not limited to,acetylacetonate-based nickel complexes, bisdithio-α-diketone-basednickel complexes, dithiolate-based nickel complexes, aminothiolate-basednickel complexes, thiocatechol-based nickel complexes,salicylaldehydeoxime-based nickel complexes, thiobisphenolate-basednickel complexes, indoaniline-based nickel compounds, carboxylicacid-based nickel salts, sulfonic acid-based nickel salts, phenol-basednickel salts, carbamic acid-based nickel salts, and dithiocarbamicacid-based nickel salts.

Among them, the nickel compounds are preferably at least one of nickelsalts of organic acids, acetylacetonate-based nickel complexes, andthiobisphenolate-based nickel complexes. In particular, in view of theeasiness of synthesis and being low in price, nickel salts of organicacids are preferred. In addition, in view of being small in molarextinction coefficient in the visible range and not absorbing the lightemission of the light source and the light-emitting material, sulfonicacid-based nickel salts are preferred. In addition, in view ofexhibiting a better singlet oxygen quenching effect, nickel salts ofaryl sulfonic acids are more preferred; in view of solubility to a widerange of solvents, nickel salts of alkyl sulfonic acids are preferred.The aryl group of the aryl sulfonic acids is preferably a substituted orunsubstituted phenyl group and more preferably a phenyl groupsubstituted by an alkyl group in view of solubility and dispersibilityto solvents.

The nickel compounds are preferably both acetylacetonate-based nickelcomplexes and thiobisphenolate-based nickel complexes in view ofsolubility to organic solvents and being small in molar extinctioncoefficient in the visible range. The ligand on nickel in thesecomplexes may be substituted by substituents such as an alkyl group, acycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenylgroup, an alkynyl group, a thiol group, an alkoxy group, an alkylthiogroup, an aryl ether group, an aryl thioether group, an aryl group, aheteroaryl group, halogen, a cyano group, an aldehyde group, a carbonylgroup, a carboxy group, an oxycarbonyl group, a carbamoyl group, anamino group, a nitro group, a silyl group, a siloxanyl group, a borylgroup, and a phosphine oxide group. These substituents may be furthersubstituted by the substituents described above.

Among them, preferred are a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group, a substituted orunsubstituted aryl group, a substituted or unsubstituted heteroarylgroup, or halogen in view of photostability, and more preferred are asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedcycloalkyl group, a substituted or unsubstituted aryl group, or halogen.In addition, more preferred are a substituted or unsubstituted alkylgroup, a substituted or unsubstituted cycloalkyl group, or halogenbecause of being less in discoloration after reaction with the singletoxygen quencher. Particularly preferred is a substituted orunsubstituted alkyl group.

Examples of a nickel compound with a molar extinction coefficient s of100 or less in the entire wavelength region of 400 nm or more and 800 nmor less include nickel salts of p-toluyl sulfonic acid, acetylacetonenickel (II) complex, hexafluoroacetylacetone nickel (II) complex,2,2′-thiobisphenolate-n-butylamine nickel (II) complex, and[2,2′-thiobis(4-tert-octylphenolate)]-2-ethylhexylamine nickel (II)complex. However, the nickel compounds are not limited to these nickelsalts and nickel complexes; compounds with a molar extinctioncoefficient c of 100 or less in the entire wavelength region of 400 nmor more and 800 nm or less among the various kinds of nickel compoundsdescribed above are suitably used.

For the lightfast stabilizers, compounds having a role as a radicalquencher can also be suitably used. Preferred examples thereof includehindered amine-based compounds. Examples of the hindered amine-basedcompounds include piperidine derivatives such as2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine,4-hydroxy-1,2,2,6,6-pentamethylpiperidine,4-methoxy-2,2,6,6-tetramethylpiperidine,4-methoxy-1,2,2,6,6-pentamethylpiperidine,bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate,2,2,6,6-tetramethyl-4-piperidyl methacrylate, and1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and oxides thereof.

In the color conversion composition and the color conversion sheetaccording to the embodiment of the present invention, the content ofthese additives, which depends on the molar extinction coefficient, theemission quantum yield, and the absorption intensity at an excitationwavelength of the compound and the thickness and the transmittance of acolor conversion sheet to be prepared, is usually preferably 1.0×10⁻³part by weight or more, more preferably 1.0×10⁻² part by weight or more,and further preferably 1.0×10⁻¹ part by weight or more relative to 100parts by weight of the binder resin. The content of the additives ispreferably 30 parts by weight or less, more preferably 15 parts byweight or less, and further preferably 10 parts by weight or lessrelative to 100 parts by weight of the binder resin.

<Base Layer>

In the color conversion sheet according to the embodiment of the presentinvention, the layer (A) and the layer (B) as the color conversion layerdescribed above are preferably formed on a base layer (the base layer 10illustrated in FIGS. 1 and 2, for example).

For the base layer, known metals, films, glasses, ceramics, papers, andthe like can be used without any particular limitation. Specifically,examples of the base layer include metal plates and foils of aluminum(including aluminum alloys), zinc, copper, iron, and the like; films ofplastics such as cellulose acetate, polyethylene terephthalate (PET),polyethylene, polyester, polyamide, polyimide, polyphenylene sulfide,polystyrene, polypropylene, polycarbonate, polyvinyl acetal, aramids,silicones, polyolefins, thermoplastic fluororesins, and a copolymer oftetrafluoroethylene and ethylene (ETFE); films of plastics ofα-polyolefin resins, polycaprolactone resins, acrylic resins, siliconeresins, and copolymerized resins of theses resins and ethylene; paperslaminated with the plastics and papers coated with the plastics; paperslaminated or deposited with the metals; and plastic films laminated ordeposited with the metals. When the base layer is a metal plate, thesurface thereof may be subjected to chromium-based or nickel-basedplating treatment or ceramic treatment.

Among these materials, in view of the easiness of preparing the colorconversion sheet and the easiness of shaping the color conversion sheet,glasses and resin films are preferably used. To exclude the possibilityof breakage or the like when a film-shaped base layer is handled, filmshaving high strength are preferred. In view of those requiredcharacteristics and economy, resin films are preferred; among them, inview of economy and handleability, preferred are plastic films selectedfrom the group consisting of PET, polyphenylene sulfide, polycarbonate,and polypropylene. When the color conversion sheet is dried or when thecolor conversion sheet is shaped under pressure at a high temperature of200° C. or more by an extruder, a polyimide film is preferred in view ofheat resistance. In view of the easiness of peeling off the sheet, thesurface of the base layer may be subjected to mold releasing treatmentin advance. Similarly, to improve inter-layer adhesiveness, the surfaceof the base layer may be subjected to highly adhesive treatment inadvance.

The thickness of the base layer is not limited to a particularthickness; the lower limit thereof is preferably 12 Lm or more and morepreferably 38 μm or more. The upper limit thereof is preferably 5,000 μmor less and more preferably 3,000 μm or less.

<Light Extraction Layer>

The color conversion sheet according to the embodiment of the presentinvention may further include a light extraction layer, in addition tothe layer (A) and the layer (B) in order to improve light extractionefficiency. The light extraction layer is a layer that reducesreflection on the boundary between two adjacent layers.

FIG. 3 is a schematic sectional view of an example in which the lightextraction layer is included in the color conversion sheet according tothe embodiment of the present invention. As illustrated in FIG. 3, thiscolor conversion sheet 1 b includes a plurality of (two in the examplein FIG. 3) base layers 10 and includes the layer (A) 11, the layer (B)12, and a light extraction layer 13 in such a manner that they areinterposed between these base layers 10. As illustrated in FIG. 3, thecolor conversion sheet 1 b preferably includes the light extractionlayer 13 between the layer (A) 11 and the layer (B) 12. In the structureexample of this color conversion sheet 1 b, the layer (A) 11, the lightextraction layer 13, and the layer (B) 12 are laminated on one baselayer 10 in this order, thereby forming a laminate with a laminationstructure of the layer (B)/the light extraction layer/the layer (A) onthis base layer 10. In addition, as illustrated in FIG. 3, another baselayer 10 is laminated on the layer (B) 12 in this laminate.

Although the laminate of the layer (A) 11, the light extraction layer13, and the layer (B) 12 is interposed between the base layers 10 in thestructure example of the color conversion sheet 1 b illustrated in FIG.3, the color conversion sheet according to the embodiment of the presentinvention is not limited to this structure example. This laminate may beformed on the base layer 10 without being interposed between the baselayers 10. The light extraction layer 13 may be formed between one endface on the upper side in the lamination direction of the layer (A) 11and one end face on the lower side in the lamination direction of thelayer (B) 12 as exemplified in FIG. 3 or formed on one end face on theupper side in the lamination direction of the layer (B) 12 or one endface on the lower side in the lamination direction of the layer (A) 11.In particular, as exemplified in FIG. 3, when the light extraction layer13 is formed between the layer (A) 11 and the layer (B) 12, the lightemission of the organic light-emitting material in the layer (A) 11efficiently enters the layer (B) 12, whereby emission loss between theselayers reduces to increase color conversion efficiency, and theluminance of white light after color conversion improves, which is thuspreferred.

When the light extraction layer 13 is formed between the layer (A) 11and the layer (B) 12, the respective refractive indices of the layer (A)11, the layer (B) 12, and the light extraction layer 13 are not limitedto particular refractive indices; when the respective refractive indicesof the layer (A) 11, the layer (B) 12, and the light extraction layer 13relative to light with a wavelength of 589.3 nm are n_(A), n_(B), andn_(C), respectively, preferably n_(A)≤n_(C)≤n_(B) or n_(B)≤n_(C)≤n_(A).In these cases, the reflection of light on the boundary between thelayer (A) 11 and the light extraction layer 13 and the boundary betweenthe layer (B) 12 and the light extraction layer 13 can be reduced.

<Barrier Layer>

The color conversion sheet according to the embodiment of the presentinvention may further include a barrier layer, in addition to the layer(A) and the layer (B). The barrier layer is used as appropriate in orderto prevent degradation by oxygen, water, and heat for the colorconversion layer exemplified by the layer (A) and the layer (B).Examples of this barrier layer include metal oxide thin films and metalnitride thin films of inorganic oxides such as silicon oxide, aluminumoxide, titanium oxide, tantalum oxide, zinc oxide, tin oxide, indiumoxide, yttrium oxide, and magnesium oxide, inorganic nitrides such assilicon nitride, aluminum nitride, titanium nitride, and silicon carbidenitride, mixtures thereof, and with other elements added thereto; andfilms formed of various kinds of resins such as polyvinyl chloride-basedresins, acrylic-based resins, silicon-based resins, melamine-basedresins, urethane-based resins, fluorine-based resins, and polyvinylalcohol-based resins such as a saponified product of vinyl acetate.

Example of a barrier resin suitably used for the barrier layer in thepresent invention include resins such as polyester, poly vinyl chloride,nylon, polyvinyl fluoride, polyvinylidene chloride, polyacrylonitrile,polyvinyl alcohol, and an ethylene-vinyl alcohol copolymer and mixturesof these resins. Among them, polyvinylidene chloride, polyacrylonitrile,an ethylene-vinyl alcohol copolymer, and polyvinyl alcohol are extremelysmall in oxygen permeability coefficient, and the barrier resinpreferably contains these resins. In addition, the barrier resin morepreferably contains polyvinylidene chloride, polyvinyl alcohol, or anethylene-vinyl alcohol copolymer because of resistance to discolorationand particularly preferably contains polyvinyl alcohol or anethylene-vinyl alcohol copolymer because of being small in environmentalloads. These resins may be contained singly or mixed with differentresins; in view of the uniformity of the film and cost, a film formed ofa single resin is more preferred.

For polyvinyl alcohol, a saponified product of polyvinyl acetate inwhich the acetyl group is saponified in 98 mol % or more can be used,for example. For the ethylene-vinyl alcohol copolymer, a saponifiedproduct of an ethylene-vinyl acetate copolymer with an ethylene contentof 20% to 50% in which the acetyl group is saponified in 98 mol % ormore can be used, for example.

Commercially available resins and films can also be used for the barrierlayer. Specific examples thereof include polyvinyl alcohol resin PVA 117manufactured by Kuraray Co., Ltd. and ethylene-vinyl alcohol copolymer(“EVAL” (registered trademark)) resins L171B and F171B and film EF-XLmanufactured by Kuraray Co., Ltd.

To the barrier layer, antioxidants, curing agents, cross-linking agents,processing-and-thermal stabilizers, lightfast stabilizers such asultraviolet absorbers, and the like may be added as needed to the extentthat they do not have an excessive influence on the light emission anddurability of the color conversion layer.

The thickness of the barrier layer, which is not limited to a particularthickness, is preferably 100 μm or less in view of the flexibility ofthe entire color conversion sheet and cost. The thickness of the barrierlayer is more preferably 50 μm or less and further preferably 20 μm orless. The thickness of the barrier layer is particularly preferably 10μm or less and may be 1 μm or less. In view of the easiness of layerformation, the thickness of the barrier layer is preferably 0.01 μm ormore.

A representative structure example of the color conversion sheet inwhich the barrier layer is included is one shown below, for example.FIG. 4 is a schematic sectional view of an example in which barrierlayers are included in the color conversion sheet according to theembodiment of the present invention. As illustrated in FIG. 4, thiscolor conversion sheet 1 c includes a plurality of (two in the examplein FIG. 4) base layers 10 and includes the layer (A) 11, the layer (B)12, and a plurality of (two in the example in FIG. 4) barrier layers 14in such a manner that they are interposed between these base layers 10.These barrier layers 14 are formed so as to interpose a laminate of thelayer (A) 11 and the layer (B) 12 therebetween from both sides in thelamination direction. In the structure example of this color conversionsheet 1 c, one barrier layer 14, the layer (A) 11, the layer (B) 12, andanother barrier layer 14 are laminated on one base layer 10 in thisorder. With this lamination, a laminate with a lamination structure ofthe barrier layer/the layer (B)/the layer (A)/the barrier layer isformed on this base layer 10. In addition, as illustrated in FIG. 4,another base layer 10 is laminated on the barrier layer 14 on the upperside in the lamination direction of this laminate.

FIG. 5 is a schematic sectional view of another example in which thebarrier layers are included in the color conversion sheet according tothe embodiment of the present invention. As illustrated in FIG. 5, thiscolor conversion sheet 1 d includes a plurality of (two in the examplein FIG. 5) base layers 10 and includes the layer (A) 11, the layer (B)12, and a plurality of (three in the example in FIG. 5) barrier layers14 in such a manner that they are interposed between these base layers10. These barrier layers 14 are formed so as to interpose the layer (A)11 therebetween from both sides in the lamination direction and tointerpose the layer (B) 12 therebetween from both sides in thelamination direction. In the structure example of this color conversionsheet 1 d, one barrier layer 14, the layer (A) 11, another barrier layer14, the layer (B) 12, and still another barrier layer 14 are laminatedon one base layer 10 in this order. With this lamination, a laminatewith a lamination structure of the barrier layer/the layer (B)/thebarrier layer/the layer (A)/the barrier layer is formed on this baselayer 10. In addition, as illustrated in FIG. 5, another base layer 10is laminated on the barrier layer 14 on the upper side in the laminationdirection of this laminate.

In the present invention, the barrier layer may be provided on eitherend face on both sides in the lamination direction of the laminate ofthe layer (A) and the layer (B) as in the barrier layers 14 exemplifiedin FIG. 4 or provided on one end face of both sides in the laminationdirection of this laminate. The barrier layer may be provided both oneither end face on both sides in the lamination direction of the layer(A) and either end face on both sides in the lamination direction of thelayer (B) as in the barrier layers 14 exemplified in FIG. 5 or providedon at least one end face of these end faces.

<Other Functional Layers>

The color conversion sheet according to the embodiment of the presentinvention may be further provided with a light diffusion layer or anauxiliary layer having an anti-reflection function, an anti-glarefunction, an anti-reflection-and-anti-glare function, a hard coatingfunction (an abrasion-resistant function), an antistatic function, asoil-resistant function, an electromagnetic shielding function, aninfrared cutting function, an ultraviolet cutting function, a polarizingfunction, or a toning function in accordance with required functions.

<Adhesive Layer>

In the color conversion sheet according to the embodiment of the presentinvention, an adhesive layer may be provided between the layers asneeded. For the adhesive layer, known materials can be used withoutparticular limitation so long as they do not have an excessive influenceon the light emission and durability of the color conversion sheet. Whenstrong adhesion is required, for example, photocurable materials,thermocurable materials, anaerobic curable materials, and thermoplasticmaterials are preferably used as the adhesive layer. Among them,thermocurable materials are more preferred, and in particular, athermocurable material that is curable at 0° C. to 150° C. is preferred.

The thickness of the adhesive layer, which is not limited a particularthickness, is preferably 0.01 μm to 100 μm, more preferably 0.01 μm to25 μm, further preferably 0.05 μm to 5 μm, and particularly preferably0.05 μm to 1 μm.

<Method for Manufacturing Color Conversion Sheet>

The following describes an example of a method for preparing the colorconversion sheet according to the embodiment of the present invention.In this method for preparing the color conversion sheet, first, acomposition for preparing the color conversion layer is prepared asfollows.

Certain amounts of materials such as the organic light-emittingmaterials, the binder resin, and a solvent described below are mixedwith each other. These materials are mixed with each other so as to givea certain composition and are then uniformly mixed and dispersed by astirring and kneading machine such as a homogenizer, arotary-and-revolutionary stirring machine, a triple roll mill, a ballmill, a planetary ball mill, or a beads mill to prepare the compositionfor preparing the color conversion layer, that is, the color conversioncomposition. After being mixed and dispersed or during being mixed anddispersed, defoaming in a vacuum or under a reduced pressure is alsopreferably performed. In addition, a specific component may be mixed inadvance, or treatment such as aging may be performed. A desired solidcontent can be obtained by removing the solvent by an evaporator.

The solvent is not limited to a particular solvent so long as it canadjust the viscosity of a resin in a fluid state and does not have anexcessive influence on the light emission and durability of alight-emitting substance. Examples of the solvent include water,2-propanol, ethanol, toluene, methyl ethyl ketone, methyl isobutylketone, cyclohexanone, hexane, acetone, terpineol, texanol, methylcellosolve, ethyl cellosolve, butyl carbitol, butyl carbitol acetate,1-methoxy-2-propanol, and propylene glycol monomethyl ether acetate. Twoor more of these solvents can be contained in combination. Toluene amongthese solvents in particular is suitably contained in view of not havingany influence on the degradation of the compound represented by GeneralFormula (1). Methyl ethyl ketone is suitably contained in view of givinga smaller amount of a residual solvent after being dried.

Next, the color conversion composition prepared by the method describedabove is applied to a substrate such as the base layer or the barrierlayer and is dried. The color conversion layer (the layer (A) and thelayer (B) used for the color conversion sheet, for example) is thusprepared. The application can be performed by a reverse roll coater, ablade coater, a slit die coater, a direct gravure coater, an offsetgravure coater, a kiss coater, a natural roll coater, an air knifecoater, a roll blade coater, a reverse roll blade coater, a two-streamcoater, a rod coater, a wire bar coater, an applicator, a dip coater, acurtain coater, a spin coater, a knife coater, or the like. To obtainthe uniformity of the film thickness of the color conversion layer, theapplication is preferably performed by a slit die coater.

The drying of the color conversion layer can be performed using ageneral heating apparatus such as a hot air drier or an infrared drier.For the heating of the color conversion sheet, a general heatingapparatus such as a hot air drier or an infrared drier is used. In thiscase, heating conditions include usually 1 minute to 5 hours at 40° C.to 250° C. and preferably 2 minutes to 4 hours at 60° C. to 200° C.Stepwise heating and curing such as step cure is also available.

After the color conversion layer is prepared, the base layer can bechanged as needed. In this case, examples of a simple method include,but are not limited to, a method that performs the change using a hotplate and a method that uses a vacuum laminator or a dry film laminator.

For a method for laminating the layers, known methods such asapplication and dry laminate can be used. The method for laminating thelayers is not limited to a particular method in the present invention;examples thereof, when Laminate (A) and Laminate (B) are laminated oneach other, include a method that forms the layer (B) on the layer (A)by application and drying, a method that forms the layer (A) on thelayer (B) by application and drying, a method that laminates aseparately formed self-supporting film for the layer (B) on the layer(A), a method that laminates a separately formed self-supporting filmfor the layer (A) on the layer (B), and a method that laminateslamination units independently prepared on each other such as laminatinga lamination unit with a lamination structure of “the base layer/thelayer (A)” and a lamination unit with a lamination structure of “thelayer (B)/base layer” on each other. To increase the stability of thecolor conversion sheet, a thermal curing process, a photocuring process,an aging process, or the like is also preferably further performed afterthe layers are laminated on each other.

<Excitation Light>

As to the type of the excitation light, any excitation light can be usedso long as it exhibits light emission in a wavelength region that can beabsorbed by the organic light-emitting materials used in the presentinvention. Excitation light from any light source can be used such ashot-cathode tubes, cold-cathode tubes, fluorescent light sources such asinorganic electroluminescence (EL) elements, organic EL element lightsources, LED light sources, incandescent light sources, sunlight, or thelike. In particular, excitation light from an LED light source ispreferred. For display and lighting uses, further preferred isexcitation light from a blue LED light source having excitation light ina wavelength range of 400 nm or more and 500 nm or less in view of thecapability of increasing the color purity of blue light.

The maximum emission wavelength of the excitation light is morepreferably 430 nm or more and 500 nm or less and further preferably 440nm or more and 500 nm or less, because the excitation energy is smallerto enable the degradation of the organic light-emitting material to beinhibited. The maximum emission wavelength of the excitation light isparticularly preferably 450 nm or more and 500 nm or less. The maximumemission wavelength of the excitation light is more preferably 480 nm orless and further preferably 470 nm or less, because the overlap of theemission spectra between the excitation light and the green light ismade small to enable color reproducibility to be improved.

The excitation light may have one emission peak or have two or moreemission peaks; to increase color purity, preferred is one having oneemission peak. A plurality of excitation light sources having differentemission peaks can be freely combined with each other.

<Light Source Unit>

The light source unit according to the embodiment of the presentinvention includes the light source and the color conversion compositionor the color conversion sheet described above. When the light sourceunit includes the color conversion composition, the method for arrangingthe light source and the color conversion composition is not limited toa particular method; the color conversion composition may be directlyapplied to the light source, or the color conversion composition may beapplied to film or glass separate from the light source. When the lightsource unit includes the color conversion sheet, the method forarranging the light source and the color conversion sheet is not limitedto a particular method; the light source and the color conversion sheetmay adhere closely to each other, or the remote phosphor method, inwhich the light source and the color conversion sheet are separate fromeach other, may be used. The light source unit may further include acolor filter for the purpose of increasing color purity.

As described above, in the color conversion sheet, the layer (B)converts the color of light emitted by either or both of the lightsource of the excitation light and the layer (A). For this reason, inthe light source unit including the light source and the colorconversion sheet, the arrangement of the light source and the layer (A)and the layer (B) included in the color conversion sheet is preferablyan arrangement in which the light source, the layer (A), and the layer(B) are arranged in this order. In this case, the color conversionefficiency of the light from the light source by the color conversionsheet is high.

As described above, the excitation light in a wavelength range of 400 nmor more and 500 nm or less has relatively small excitation energy andcan thus prevent the decomposition of the light-emitting substance suchas the compound represented by General Formula (1). Consequently, thelight source included in the light source unit is preferably alight-emitting diode having its maximum emission in a wavelength rangeof 400 nm or more and 500 nm or less. In addition, this light sourcepreferably has maximum emission in a wavelength range of 430 nm or moreand 480 nm or less and further preferably has maximum emission in awavelength range of 450 nm or more and 470 nm or less. The light sourceunit of the present invention can be used for displays, lighting, theinterior design, signs, signboards, and the like and is suitably usedfor displays and lighting in particular.

<Display and Lighting Apparatus>

The display according to the embodiment of the present inventionincludes the light source unit including the light source and the colorconversion sheet as described above. For a display such as a liquidcrystal display, for example, the light source unit described above isused as a backlight unit.

A display according to the embodiment of the present invention canachieve higher luminance than a display exhibiting the same degree ofcolor reproducibility using other technical means. Because of this,using a display according to the embodiment of the present invention asa small display for television sets, monitors, personal computers,tablet personal computers, smartphones, mobile phones, and other mobiledevices makes it possible to achieve an improvement in power efficiency.In particular, mobile devices such as laptop personal computers, tabletpersonal computers, and smartphones require high power efficiency, andaccordingly a display according to the embodiment of the presentinvention can be suitably used for such devices. Accordingly, one of thepreferable aspects of a display according to the embodiment of thepresent invention is, without particular limitation, a screen size of 20inches or less. High power efficiency in particular is required, andaccordingly, the screen size is more preferably 16 inches or less,further preferably 14 inches or less. The lower limit of the screen sizeis not limited to a particular value, and is preferably 4 inches or morebecause such a size makes it possible to make good use of an imagehaving high color reproducibility.

Another preferable aspect of a display according to the embodiment ofthe present invention is that the display has a color gamut coverage of96% or more in the (u′,v′) color space with respect to the DCI-P3 colorgamut standard. A color conversion sheet according to the embodiment ofthe present invention involves use of an organic light-emitting materialhaving high color purity, and accordingly, can make the concentration ofa color filter lower in cases where the color conversion sheet isincorporated in a light source unit as above-mentioned. This results inachieving high color reproducibility, i.e. a color gamut coverage of 96%or more with respect to the DCI-P3 color gamut standard, andaccordingly, makes it possible to achieve higher luminance than use of aknown technology. A color gamut coverage of 97% or more in the (u′,v′)color space with respect to the DCI-P3 color gamut standard produces alarger effect of achieving higher luminance, and accordingly, is morepreferable. A color gamut coverage of 98% or more in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard produces an evenlarger effect of producing higher luminance, and accordingly, isparticularly preferable.

The lighting apparatus according to the embodiment of the presentinvention includes the light source unit including the light source andthe color conversion sheet as described above. This lighting apparatusis configured to emit white light by combining a blue LED light sourceas the light source unit and the color conversion sheet or the colorconversion composition that converts blue light from this blue LED lightsource into light with a wavelength longer than that of the blue lightwith each other, for example.

EXAMPLES

The following describes the present invention with reference toExamples; these Examples do not limit the present invention. In thefollowing Examples and Comparative Examples, Compounds G-1, G-2, G-3,R-1, and R-2 are compounds shown below.

The following describes methods of evaluation about structural analysisin the Examples and the Comparative Examples.

<Measurement of ¹H-NMR>

¹H-NMR on the compounds was measured with a deuteriochloroform solutionusing Superconducting FTNMR EX-270 (manufactured by JEOL Ltd.).

<Measurement of Absorption Spectrum>

Absorption spectra of the compounds were measured with the compoundsdissolved in toluene at a concentration of 1×10⁻⁶ mol/L using U-3200type spectrophotometer (manufactured by Hitachi, Ltd.).

<Measurement of Fluorescence Spectrum>

For fluorescence spectra of the compounds, fluorescence spectra when thecompounds were dissolved in toluene at a concentration of 1×10⁻⁶ mol/Land were excited at a wavelength of 460 nm were measured using F-2500type fluorescence spectrophotometer (manufactured by Hitachi, Ltd.).

<Measurement of Refractive Index of Resin>

The refractive index of resins such as the binder resin was measured asa refractive index relative to light with a wavelength of 589.3 nm of aresin film formed by applying it to a PET film using a reflectancespectrometer FE-3000 (manufactured by Otsuka Electronics Co., Ltd.). Theresin film had an average film thickness of 30 μm and was formed byapplying a resin solution to “Lumirror” U48 (manufactured by TorayIndustries, Inc., thickness: 50 μm) using a Baker applicator and washeated and dried at 100° C. for 20 minutes.

<Measurement of Color Conversion Characteristics>

In the measurement of color conversion characteristics, with each of thecolor conversion sheets and a prism sheet mounted on a planarlight-emitting device installing a blue LED element with an emissionpeak wavelength of 447 nm, a current of 30 mA was passed through thisplanar light-emitting device to light up this blue LED element, and anemission spectrum, chromaticity, and luminance were measured using aspectral radiance meter (CS-1000 manufactured by Konica Minolta, Inc.).

<Calculation of Color Gamut>

From the emission spectrum obtained by the measurement of the colorconversion characteristics and the spectral data of the transmittance ofa color filter, a color gamut in the (u′,v′) color space when colorpurity was improved by the color filter was calculated. The calculatedcolor gamut in the (u′,v′) color space was evaluated based on thefollowing criteria by a coverage with respect to the DCI-P3 color gamutstandard. As an evaluation result of the color gamut in this (u′,v′)color space, “A” indicates that the coverage is 98% or more. “B”indicates that the coverage is 97% or more and less than 98%. “C”indicates that the coverage is 96% or more and less than 97%. “D”indicates that the coverage is less than 96%. In this evaluation result,a higher coverage indicates a wider color gamut and that the colorreproducibility of the color conversion sheet is more favorable.

Synthesis Example 1

The following describes a method for synthesizing Compound G-1 ofSynthesis Example 1 of the present invention. In the method forsynthesizing Compound G-1, 3,5-dibromobenzaldehyde (3.0 g),4-t-butylphenylboronic acid (5.3 g),tetrakis(triphenylphosphine)palladium (0) (0.4 g), and potassiumcarbonate (2.0 g) were put into a flask, which was purged with nitrogen.Degassed toluene (30 mL) and degassed water (10 mL) were added thereto,and the resultant mixture was refluxed for 4 hours. This reactionsolution was cooled to room temperature, and an organic layer wasseparated and was then washed with a saturated saline solution. Thisorganic layer was dried with magnesium sulfate and was filtered, and thesolvent was then distilled off therefrom. The obtained reaction productwas purified by silica gel chromatography to obtain3,5-bis(4-t-butylphenyl)benzaldehyde (3.5 g) as a white solid.

Next, 3,5-bis(4-t-butylphenyl)benzaldehyde (1.5 g) and2,4-dimethylpyrrole (0.7 g) were put into a reaction solution, anddehydrated dichloromethane (200 mL) and trifluoroacetic acid (one drop)were added thereto, and the resultant mixture was stirred for 4 hours ina nitrogen atmosphere. Subsequently, a dehydrated dichloromethanesolution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (0.85 g) was addedthereto, and the resultant mixture was stirred for additional 1 hour.After completion of reaction, a boron trifluoride diethyl ether complex(7.0 mL) and diisopropylethylamine (7.0 mL) were added thereto, and theresultant mixture was stirred for 4 hours. Water (100 mL) was thenfurther added thereto, the resultant mixture was stirred, and an organiclayer was separated. This organic layer was dried with magnesium sulfateand was filtered, and the solvent was then distilled off therefrom. Theobtained reaction product was purified by silica gel chromatography toobtain a compound (0.4 g) (yield: 18%). A ¹H-NMR analysis result of thisobtained compound is as follows, by which it was confirmed that thiscompound was Compound G-1.

¹H-NMR (CDCl₃, ppm): 7.95 (s, 1H), 7.63-7.48 (m, 10H), 6.00 (s, 2H),2.58 (s, 6H), 1.50 (s, 6H), 1.37 (s, 18H).

An absorption spectrum of this compound G-1 is as illustrated in FIG. 6,which showed light absorption characteristics against a blue excitationlight source (460 nm). A fluorescence spectrum of this compound G-1 isas illustrated in FIG. 7, which showed a sharp emission peak in thegreen region. Showing an emission quantum yield of 83%, this CompoundG-1 was a compound that enabled efficient color conversion.

Synthesis Example 2

The following describes a method for synthesizing Compound R-1 ofSynthesis Example 2 of the present invention. In the method forsynthesizing Compound R-1, a mixed solution of4-(4-t-butylphenyl)-2-(4-methoxyphenyl)pyrrole (300 mg),2-methoxybenzoyl chloride (201 mg), and toluene (10 mL) was heated at120° C. for 6 hours in a nitrogen flow. This heated solution was cooledto room temperature and was then evaporated. Next, the resultantconcentrate was washed with ethanol (20 mL) and was dried in a vacuum toobtain2-(2-methhoxybenzoyl)-3-(4-t-butylphenyl)-5-(4-methoxyphenyl)pyrrole(260 mg).

Next, a mixed solution of2-(2-methhoxybenzoyl)-3-(4-t-butylphenyl)-5-(4-methoxyphenyl)pyrrole(260 mg), 4-(4-t-butylphenyl)-2-(4-methoxyphenyl)pyrrole (180 mg),methanesulfonic acid anhydride (206 mg), and degassed toluene (10 mL)was heated at 125° C. for 7 hours in a nitrogen flow. This heatedsolution was cooled to room temperature, water (20 mL) was then injectedthereto, and an organic layer was extracted with dichloromethane (30mL). This organic layer was washed with water (20 L) twice and wasevaporated, and the resultant concentrate was dried in a vacuum toobtain a pyrromethene body.

Next, to a mixed solution of the obtained pyrromethene body and toluene(10 mL) in a nitrogen stream, diisopropylethylamine (305 mg) and a borontrifluoride diethyl ether complex (670 mg) were added, and the resultantmixture was stirred at room temperature for 3 hours. Water (20 mL) wasthen injected thereinto, and an organic layer was extracted withdichloromethane (30 mL). This organic layer was washed with water (20mL) twice, was dried with magnesium sulfate, and was evaporated.Subsequently, the resultant concentrate was purified by silica gelchromatography and was dried in a vacuum to obtain reddish-violet powder(0.27 g). A ¹H-NMR analysis result of the obtained reddish-violet powderis as follows, by which it was confirmed that the reddish-violet powderobtained as above was Compound R-1.

¹H-NMR (CDCl₃, ppm): 1.19 (s, 18H), 3.42 (s, 3H), 3.85 (s, 6H), 5.72 (d,1H), 6.20 (t, 1H), 6.42-6.97 (m, 16H), 7.89 (d, 4H).

An absorption spectrum of this compound R-1 is as illustrated in FIG. 8,which showed light absorption characteristics against blue and greenexcitation light sources. A fluorescence spectrum of this compound R-1is as illustrated in FIG. 9, which showed a sharp emission peak in thered region. Showing an emission quantum yield of 90%, this Compound R-1was a compound that enabled efficient color conversion.

The compounds G-2 and R-2 were synthesized using a known method in thesame manner as in the Synthesis Example. As G-3, a product having apurity of 98% was purchased from Sigma-Aldrich Co. LLC and used.

Example 1

In Example 1 of the present invention, using Polyester Resin T11 (SPvalue=10.7 (cal/cm³)^(0.5)) as a binder resin, 0.25 part by weight ofCompound G-1 as the organic light-emitting material (a) and 100 parts byweight of methyl ethyl ketone as a solvent were mixed with 100 parts byweight of this binder resin. Subsequently, the mixture of these wasstirred and defoamed at 300 rpm for 20 minutes using a planetarystirring and defoaming apparatus “Mazerustar KK-400” (manufactured byKurabo Industries Ltd.) to obtain a color conversion composition for thelayer (A) preparation.

Similarly, using Acrylic Resin T1 (SP value=9.5 (cal/cm³)^(0.5)) as abinder resin, 0.03 part by weight of Compound R-1 as the organiclight-emitting material (b) and 300 parts by weight of toluene as asolvent were mixed with 100 parts by weight of this binder resin.Subsequently, the mixture of these was stirred and defoamed at 300 rpmfor 20 minutes using a planetary stirring and defoaming apparatus“Mazerustar KK-400” (manufactured by Kurabo Industries Ltd.) to obtain acolor conversion composition for the layer (B) preparation.

Next, the color conversion composition for the layer (A) preparation wasapplied to “Lumirror” U48 (manufactured by Toray Industries, Inc.,thickness: 50 μm) as the base layer A using a slit die coater and washeated and dried at 100° C. for 20 minutes to form the layer (A) with anaverage film thickness of 15 μm. A laminate unit including the baselayer A and the layer (A) was thus prepared.

Similarly, the color conversion composition for the layer (B)preparation was applied to the PET base layer side (the base layer Bside) of “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer using a slit die coater and was heated anddried at 100° C. for 20 minutes to form the layer (B) with an averagefilm thickness of 13 μm. A laminate unit including the light diffusionlayer, the base layer B, and the layer (B) was thus prepared.

Next, the above two units were laminated by heating so as to laminatethe layer (A) and the layer (B) directly on each other. With thislamination, a color conversion sheet having a structure of “the baselayer A/the layer (A)/the layer (B)/the base layer B/the light diffusionlayer” was prepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; the emissionspectrum showed sharp emission peaks in the red region, the greenregion, and the blue region as illustrated in FIG. 10, by which whitelight with XY color coordinates of (X,Y)=(0.25,0.22) was obtained. Whenonly the emission region of green light was extracted, high color puritygreen emission with a peak wavelength of 530 nm and with a full width athalf maximum of an emission spectrum at the peak wavelength being 29 nmwas obtained. When only the emission region of red light was extracted,high color purity red emission with a peak wavelength of 630 nm and witha full width at half maximum of an emission spectrum at the peakwavelength being 49 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 98%. Anevaluation result of Example 1 is listed in Table 3 below. In Table 3,“Color Coordinates (X,Y)” are the values of the XY color coordinates.“Color Gamut Coverage” is a coverage in the (u′,v′) color space withrespect to the DCI-P3 color gamut standard. “A” to “C” in the column of“Color Gamut Coverage” show evaluation results of this color gamutcoverage. The same holds true for all the tables. With the luminance ofthe white light after color conversion in Example 1 as 100%, Example 1was compared with Examples 2 to 13 and Comparative Examples 1 to 3described below in luminance to afford a “Relative Luminance”.

Examples 2 to 7 and Comparative Example 1

In Examples 2 to 7 of the present invention and Comparative Example 1against the present invention, color conversion sheets were prepared andevaluated similarly to Example 1 except that the organic light-emittingmaterials (Compounds G-1, G-2, and G-3) listed in Table 3 were used asappropriate as the organic light-emitting material (a) of the layer (A),that the organic light-emitting materials (Compounds R-1 and R-2) listedin Table 3 were used as appropriate as the organic light-emittingmaterial (b) of the layer (B), that the binder resins (Acrylic Resin T1,Acrylic Resin T2, Polyester Resin T11, Polyester Resin T12, CycloolefinResin T21, and Phenoxy Resin T31) listed in Table 3 were used asappropriate as the respective binder resins of the layer (A) and thelayer (B), and that the film thickness of each layer was adjusted sothat the XY color coordinates of white light could be (X,Y)=(0.25,0.22)in measurement of the color conversion characteristics. Evaluationresults of Examples 2 to 7 and Comparative Example 1 are listed in Table3.

Comparative Example 2

In Comparative Example 2 against the present invention, using PolyesterResin T11 (SP value=10.7 (cal/cm³)^(0.5)) as a binder resin, 0.25 partby weight of Compound G-1 as the organic light-emitting material (a),0.014 part by weight of Compound R-1 as the organic light-emittingmaterial (c), and 100 parts by weight of methyl ethyl ketone as asolvent were mixed with 100 parts by weight of this binder resin.Subsequently, the mixture of these was stirred and defoamed at 300 rpmfor 20 minutes using a planetary stirring and defoaming apparatus“Mazerustar KK-400” (manufactured by Kurabo Industries Ltd.) to obtain acolor conversion composition for color conversion layer preparation.

Next, the color conversion composition for color conversion layerpreparation was applied to “Lumirror” U48 (manufactured by TorayIndustries, Inc., thickness: 50 μm) as the base layer A using a slit diecoater and was heated and dried at 100° C. for 20 minutes to form acolor conversion layer with an average film thickness of 16 μm. Alaminate unit including the base layer A and the color conversion layerwas thus prepared.

Next, “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer and the unit were laminated by heating so asto laminate the base layer B side of the light diffusion film and thecolor conversion layer side of the unit directly on each other. Withthis lamination, a color conversion sheet having a structure of “thebase layer A/the color conversion layer/the base layer B/the lightdiffusion layer” was prepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; white light withXY color coordinates of (X,Y)=(0.25,0.22) was obtained. When only theemission region of green light was extracted, high color purity greenemission with a peak wavelength of 532 nm and with a full width at halfmaximum of an emission spectrum at the peak wavelength being 33 nm wasobtained. When only the emission region of red light was extracted, highcolor purity red emission with a peak wavelength of 633 nm and with afull width at half maximum of an emission spectrum at the peakwavelength being 50 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 95%. Anevaluation result of Comparative Example 2 is listed in Table 3.

Comparative Example 3

In Comparative Example 3 against the present invention, color conversionsheets were prepared and evaluated similarly to Comparative Example 2except that the organic light-emitting materials (Compounds G-3 and R-1)listed in Table 3 were used as the organic light-emitting material (a).An evaluation result of Comparative Example 3 is listed in Table 3.

Example 8

In Example 8 of the present invention, using Polyester Resin T11 (SPvalue=10.7 (cal/cm³)^(0.5)) as a binder resin, 0.25 part by weight ofCompound G-1 as the organic light-emitting material (a), 0.008 part byweight of Compound R-1 as the organic light-emitting material (c), and100 parts by weight of methyl ethyl ketone as a solvent were mixed with100 parts by weight of this binder resin. Subsequently, the mixture ofthese was stirred and defoamed at 300 rpm for 20 minutes using aplanetary stirring and defoaming apparatus “Mazerustar KK-400”(manufactured by Kurabo Industries Ltd.) obtain a color conversioncomposition for the layer (A) preparation.

Similarly, using Acrylic Resin T1 (SP value=9.5 (cal/cm³)^(0.5)) as abinder resin, 0.018 part by weight of Compound R-1 as the organiclight-emitting material (b) and 300 parts by weight of toluene as asolvent were mixed with 100 parts by weight of this binder resin.Subsequently, the mixture of these was stirred and defoamed at 300 rpmfor 20 minutes using a planetary stirring and defoaming apparatus“Mazerustar KK-400” (manufactured by Kurabo Industries Ltd.) to obtain acolor conversion composition for the layer (B) preparation.

Next, the color conversion composition for the layer (A) preparation wasapplied to “Lumirror” U48 (manufactured by Toray Industries, Inc.,thickness: 50 μm) as the base layer A using a slit die coater and washeated and dried at 100° C. for 20 minutes to form the layer (A) with anaverage film thickness of 15 μm. A laminate unit including the baselayer A and the layer (A) was thus prepared.

Similarly, the color conversion composition for the layer (B)preparation was applied to the PET base layer side (the base layer Bside) of “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer using a slit die coater and was heated anddried at 100° C. for 20 minutes to form the layer (B) with an averagefilm thickness of 13 μm. A laminate unit including the light diffusionlayer, the base layer B, and the layer (B) was thus prepared.

Next, the above two units were laminated by heating so as to laminatethe layer (A) and the layer (B) directly on each other. With thislamination, a color conversion sheet having a structure of “the baselayer A/the layer (A)/the layer (B)/the base layer B/the light diffusionlayer” was prepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; an emissionspectrum similar to that in FIG. 10 was obtained, by which white lightwith XY color coordinates of (X,Y)=(0.25,0.22) was obtained. When onlythe emission region of green light was extracted, high color puritygreen emission with a peak wavelength of 530 nm and with a full width athalf maximum of an emission spectrum at the peak wavelength being 29 nmwas obtained. When only the emission region of red light was extracted,high color purity red emission with a peak wavelength of 632 nm and witha full width at half maximum of an emission spectrum at the peakwavelength being 51 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 99%. Anevaluation result of Example 8 is listed in Table 3.

Example 9

In Example 9 of the present invention, using Polyester Resin T11 (SPvalue=10.7 (cal/cm³)^(0.5)) as a binder resin, 0.25 part by weight ofCompound G-1 as the organic light-emitting material (a) and 100 parts byweight of methyl ethyl ketone as a solvent were mixed with 100 parts byweight of this binder resin. Subsequently, the mixture of these wasstirred and defoamed at 300 rpm for 20 minutes using a planetarystirring and defoaming apparatus “Mazerustar KK-400” (manufactured byKurabo Industries Ltd.) obtain a color conversion composition for thelayer (A) preparation.

Similarly, using Acrylic Resin T1 (SP value=9.5 (cal/cm³)^(0.5)) as abinder resin, 0.03 part by weight of Compound R-1 as the organiclight-emitting material (b), 0.015 part by weight of Compound G-1 as theorganic light-emitting material (d), and 300 parts by weight of tolueneas a solvent were mixed with 100 parts by weight of this binder resin.Subsequently, the mixture of these was stirred and defoamed at 300 rpmfor 20 minutes using a planetary stirring and defoaming apparatus“Mazerustar KK-400” (manufactured by Kurabo Industries Ltd.) to obtain acolor conversion composition for the layer (B) preparation.

Next, the color conversion composition for the layer (A) preparation wasapplied to “Lumirror” U48 (manufactured by Toray Industries, Inc.,thickness: 50 μm) as the base layer A using a slit die coater and washeated and dried at 100° C. for 20 minutes to form the layer (A) with anaverage film thickness of 15 μm. A laminate unit including the baselayer A and the layer (A) was thus prepared.

Similarly, the color conversion composition for the layer (B)preparation was applied to the PET base layer side (the base layer Bside) of “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer using a slit die coater and was heated anddried at 100° C. for 20 minutes to form the layer (B) with an averagefilm thickness of 11 μm. A laminate unit including the light diffusionlayer, the base layer B, and the layer (B) was thus prepared.

Next, the above two units were laminated by heating so as to laminatethe layer (A) and the layer (B) directly on each other. With thislamination, a color conversion sheet having a structure of “the baselayer A/the layer (A)/the layer (B)/the base layer B/the light diffusionlayer” was prepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; an emissionspectrum similar to that in FIG. 10 was obtained, by which white lightwith XY color coordinates of (X,Y)=(0.25,0.22) was obtained. When onlythe emission region of green light was extracted, high color puritygreen emission with a peak wavelength of 532 nm and with a full width athalf maximum of an emission spectrum at the peak wavelength being 30 nmwas obtained. When only the emission region of red light was extracted,high color purity red emission with a peak wavelength of 630 nm and witha full width at half maximum of an emission spectrum at the peakwavelength being 50 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 97%. Anevaluation result of Example 9 is listed in Table 3.

Examples 12 and 13

In Examples 12 and 13 of the present invention, color conversion sheetswere prepared and evaluated similarly to Example 1 except that thebinder resins (Acrylic Resin T1, Polyester Resin T11, and Phenoxy ResinT31) listed in Table 3 were used as appropriate as the respective binderresins of the layer (A) and the layer (B), and that the film thicknessof each layer was adjusted so that the XY color coordinates of whitelight could be (X,Y)=(0.25,0.22) in measurement of the color conversioncharacteristics. Evaluation results of Examples 12 and 13 are listed inTable 3.

Examples 1 to 3, in which the organic light-emitting materialsexhibiting light emission with high color purity (Compounds G-1, G-2,R-1, and R-2) were used and in which the relation of the SP values ofthe binder resins was SP_(A)>SP_(B) for the layer (A) and the layer (B),were able to achieve both a wide color gamut, which is represented by acoverage of 98% or more in the (u′,v′) color space with respect to theDCI-P3 color gamut standard, and a high luminance. On the other hand, inComparative Example 1, in which the relation of the SP values wasSP_(A)<SP_(B), the color gamut was wide, but the luminance was 15% lowerthan in Example 1, with the result that Comparative Example 1 was notable to succeed in both a color gamut and luminance. Furthermore, inComparative Example 2, in which a plurality of organic light-emittingmaterials (Compound G-1 and Compound R-1) were dispersed in the singlelayer, the luminance was comparatively high, but the color gamutcoverage was approximately 95% with respect to the DCI-P3 color gamutstandard, also with the result that Comparative Example 2 was not ableto succeed in both a color gamut and luminance.

In Example 4, Compound G-3 was used as the organic light-emittingmaterial (a), and Compound R-1 was used as the organic light-emittingmaterial (b). Consequently, Example 4 was not as good as Examples 1 to3, in which Compounds G-1 and G-2 exhibiting light emission with highcolor purity were used as the organic light-emitting material (a), butwas able to improve both the color gamut and luminance, compared withComparative Example 3 in which a plurality of organic light-emittingmaterials (Compound G-3 and Compound R-1) were dispersed in the singlelayer.

In Example 5, the organic light-emitting materials exhibiting lightemission with high color purity (Compounds G-1 and R-1) were used, anacrylic resin having an SP value of 9.9 was used for the layer (A), andan acrylic resin having an SP value of 9.5 was used for the layer (B).As a result, the light emission of Compound G-1 had a shorter wavelengththan in Example 1, in which a polyester resin having an SP value of 10.7was used for the layer (A). Accordingly, the visibility was lower, andthe luminance was a little lower, but Example 5 was able to achieve botha wide color gamut and high luminance.

In Example 6, the organic light-emitting materials exhibiting lightemission with high color purity (Compounds G-1 and R-1) were used, anacrylic resin having an SP value of 9.5 was used for the layer (A), anda cycloolefin resin having an SP value of 8.9 was used for the layer(B). As a result, the dispersibility of Compound R-1 was worse than inExample 5, in which an acrylic resin having an SP value of 9.5 was usedfor the layer (B). Accordingly, the emission efficiency was lower, andthe luminance was a little lower, but Example 6 was able to achieve botha wide color gamut and high luminance.

In Example 7, the organic light-emitting materials exhibiting lightemission with high color purity (Compounds G-1 and R-1) were used, apolyester resin having an SP value of 10.9 was used for the layer (A),and a polyester resin having an SP value of 10.7 was used for the layer(B). As a result, the light emission of Compound R-1 had a longerwavelength than in Example 1, in which an acrylic resin having an SPvalue of 9.5 was used for the layer (B). Accordingly, the visibility waslower, and the luminance was lower, but Example 7 was able to achieveboth a wide color gamut and high luminance.

In Examples 8 and 9, the organic light-emitting materials exhibitinglight emission with high color purity (Compounds G-1 and R-1) were used,the relation of the SP values of the binder resins was SP_(A)>SP_(B) forthe layer (A) and the layer (B), and besides a plurality of organiclight-emitting materials were mixed in either the layer (A) or the layer(B). As a result, fine adjustment of the peak wavelength of the lightemission became possible, Example 8 made it possible to afford a widercolor gamut than Example 1, with the luminance substantially maintained,and Example 9 made it possible to improve luminance more than Example 1,with the coverage of 97% or more maintained with respect to the DCI-P3color gamut standard.

In Example 12, the organic light-emitting materials exhibiting lightemission with high color purity (Compounds G-1 and R-1) were used, aphenoxy resin having an SP value of 10.9 was used for the layer (A), andan acrylic resin having an SP value of 9.5 was used for the layer (B).As a result, the light emission of Compound G-1 had an excessivelylonger wavelength than in Example 1, in which a polyester resin was usedfor the layer (A). Accordingly, the color gamut became narrower, thetransparency of the binder resin was lower, and thus, the luminancedecreased, but Example 12 was able to achieve both a wide color gamutand high luminance.

In Example 13, the organic light-emitting materials exhibiting lightemission with high color purity (Compounds G-1 and R-1) were used, aphenoxy resin having an SP value of 10.9 was used for the layer (A), anda polyester resin having an SP value of 10.7 was used for the layer (B).As a result, the light emission of Compound G-1 had an excessivelylonger wavelength than in Example 1, in which a polyester resin was usedfor the layer (A). Accordingly, the color gamut became narrower. Thelight emission of Compound R-1 also had a longer wavelength than inExample 1, in which an acrylic resin having an SP value of 9.5 was usedfor the layer (B). Accordingly, the visibility was lower, the luminancewas lower, but Example 13 was able to achieve both a wide color gamutand high luminance.

TABLE 3 Layer (A) Layer (B) Organic Organic Light-emittingLight-emitting Material Material Peak Wavelength (nm) (a) (c) BinderResin (b) (d) Binder Resin Green Red Example 1 G-1 — Polyester R-1 —Acrylic 530 630 Resin T11 (SP Resin T1 (SP Value = 10.7) Value = 9.5)Example 2 G-2 — Polyester R-1 — Acrylic 530 630 Resin T11 (SP Resin T1(SP Value = 10.7) Value = 9.5) Example 3 G-1 — Polyester R-2 — Acrylic530 632 Resin T11 (SP Resin T1 (SP Value = 10.7) Value = 9.5) Example 4G-3 — Polyester R-1 — Acrylic 507 629 Resin T11 (SP Resin T1 (SP Value =10.7) Value = 9.5) Example 5 G-1 — Acrylic R-1 — Acrylic 527 629 ResinT2 (SP Resin T1 (SP Value = 9.9) Value = 9.5) Example 6 G-1 — AcrylicR-1 — Cycloolefin 527 627 Resin T1 (SP Resin T21 (SP Value = 9.5) Value= 8.9) Example 7 G-1 — Polyester R-1 — Polyester 531 639 Resin T12 (SPResin T11 (SP Value = 10.9) Value =10.7) Example 8 G-1 R-1 Polyester R-1— Acrylic 530 632 Resin T11 (SP Resin T1 (SP Value = 10.7) Value = 9.5)Example 9 G-1 — Polyester R-1 G-1 Acrylic 532 630 Resin T11 (SP Resin T1(SP Value = 10.7) Value = 9.5) Example 12 G-1 — Phenoxy R-1 — Acrylic532 630 Resin T31 (SP Resin T1 (SP Value = 10.9) Value = 9.5) Example 13G-1 — Phenoxy R-1 — Polyester 533 639 Resin T31 (SP Resin T11 (SP Value= 10.9) Value = 10.7) Comparative G-1 — Acrylic R-1 — Phenoxy 527 643Example 1 Resin T1 (SP Resin T31 (SP Value = 9.5) Value = 10.9)Comparative G-1 R-1 Polyester — — — 532 633 Example 2 Resin T11 (SPValue = 10.7) Comparative G-3 R-1 Polyester — — — 507 632 Example 3Resin T11 (SP Value = 10.7) Full Width at Color Half Maximum (nm)Coordinates Color Gamut Relative Green Red (X, Y) Coverage LuminanceExample 1 29 49 (0.25, 0.22) 98% A 100%  Example 2 29 49 (0.25, 0.22)98% A 99% Example 3 29 50 (0.25, 0.22) 98% A 98% Example 4 55 51 (0.25,0.22) 96% C 83% Example 5 29 49 (0.25, 0.22) 98% A 94% Example 6 29 49(0.25, 0.22) 97% B 92% Example 7 29 50 (0.25, 0.22) 99% A 90% Example 829 51 (0.25, 0.22) 99% A 99% Example 9 30 50 (0.25, 0.22) 97% B 102% Example 12 30 50 (0.25, 0.22) 97% B 98% Example 13 30 50 (0.25, 0.22)97% B 88% Comparative 27 50 (0.25, 0.22) 99% A 82% Example 1 Comparative33 50 (0.25, 0.22) 95% D 96% Example 2 Comparative 56 50 (0.25, 0.22)94% D 74% Example 3

Example 10

In Example 10 of the present invention, using Polyester Resin T12 (SPvalue=10.9 (cal/cm³)^(0.5), refractive index n_(A)=2.42) as a binderresin, 0.3 part by weight of Compound G-2 as the organic light-emittingmaterial (a) and 100 parts by weight of methyl ethyl ketone as a solventwere mixed with 100 parts by weight of this binder resin. Subsequently,the mixture of these was stirred and defoamed at 300 rpm for 20 minutesusing a planetary stirring and defoaming apparatus “Mazerustar KK-400”(manufactured by Kurabo Industries Ltd.) obtain a color conversioncomposition for the layer (A) preparation.

Similarly, using Acrylic Resin T2 (SP value=9.9 (cal/cm³)^(0.5),refractive index n_(B)=2.22) as a binder resin, 0.03 part by weight ofCompound R-1 as the organic light-emitting material (b) and 300 parts byweight of toluene as a solvent were mixed with 100 parts by weight ofthis binder resin. Subsequently, the mixture of these was stirred anddefoamed at 300 rpm for 20 minutes using a planetary stirring anddefoaming apparatus “Mazerustar KK-400” (manufactured by KuraboIndustries Ltd.) to obtain a color conversion composition for the layer(B) preparation.

Next, the color conversion composition for the layer (A) preparation wasapplied to “Lumirror” U48 (manufactured by Toray Industries, Inc.,thickness: 50 μm) as the base layer A using a slit die coater and washeated and dried at 100° C. for 20 minutes to form the layer (A) with anaverage film thickness of 15 μm. A laminate unit including the baselayer A and the layer (A) was thus prepared.

Similarly, the color conversion composition for the layer (B)preparation was applied to the PET base layer side (the base layer Bside) of “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer using a slit die coater and was heated anddried at 100° C. for 20 minutes to form the layer (B) with an averagefilm thickness of 13 μm. A laminate unit including the light diffusionlayer, the base layer B, and the layer (B) was thus prepared.

Next, the above two units were laminated by heating so as to laminatethe layer (A) and the layer (B) directly on each other. With thislamination, a color conversion sheet having a structure of “the baselayer A/the layer (A)/the layer (B)/the base layer B/the light diffusionlayer” was prepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; an emissionspectrum similar to that in FIG. 10 was obtained, by which white lightwith XY color coordinates of (X,Y)=(0.25,0.22) was obtained. When onlythe emission region of green light was extracted, high color puritygreen emission with a peak wavelength of 530 nm and with a full width athalf maximum of an emission spectrum at the peak wavelength being 29 nmwas obtained. When only the emission region of red light was extracted,high color purity red emission with a peak wavelength of 630 nm and witha full width at half maximum of an emission spectrum at the peakwavelength being 49 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 98%. With theluminance of the white light after color conversion in this Example 10as 100, Example 10 and Example 11 described below were compared witheach other in luminance. An evaluation result of Example 10 is listed inTable 4 below. In Table 4, “Relative Luminance (%)” is relativeluminance between Example 10 and Example 11.

Example 11

In Example 11 of the present invention, using Polyester Resin T12 (SPvalue=10.9 (cal/cm³)^(0.5), refractive index n_(A)=2.42) as a binderresin, 0.3 part by weight of Compound G-2 as the organic light-emittingmaterial (a) and 100 parts by weight of methyl ethyl ketone as a solventwere mixed with 100 parts by weight of this binder resin. Subsequently,the mixture of these was stirred and defoamed at 300 rpm for 20 minutesusing a planetary stirring and defoaming apparatus “Mazerustar KK-400”(manufactured by Kurabo Industries Ltd.) to obtain a color conversioncomposition for the layer (A) preparation.

Similarly, using Acrylic Resin T2 (SP value=9.9 (cal/cm³)^(0.5),refractive index n_(B)=2.22) as a binder resin, 0.03 part by weight ofCompound R-1 as the organic light-emitting material (b) and 300 parts byweight of toluene as a solvent were mixed with 100 parts by weight ofthis binder resin. Subsequently, the mixture of these was stirred anddefoamed at 300 rpm for 20 minutes using a planetary stirring anddefoaming apparatus “Mazerustar KK-400” (manufactured by KuraboIndustries Ltd.) to obtain a color conversion composition for the layer(B) preparation.

In addition, using Polyester Resin T13 (SP value=10.6 (cal/cm³)^(0.5),refractive index n_(C)=2.32) as a resin for a light extraction layer, 50parts by weight of toluene and 50 parts by weight of1-methoxy-2-propanol as solvents were mixed with 100 parts by weight ofthis resin. Subsequently, the mixture of these was stirred and defoamedat 300 rpm for 20 minutes using a planetary stirring and defoamingapparatus “Mazerustar KK-400” (manufactured by Kurabo Industries Ltd.)to obtain a composition for light extraction layer preparation.

Next, the color conversion composition for the layer (A) preparation wasapplied to “Lumirror” U48 (manufactured by Toray Industries, Inc.,thickness: 50 μm) as the base layer A using a slit die coater and washeated and dried at 100° C. for 20 minutes to form the layer (A) with anaverage film thickness of 15 μm. A laminate unit including the baselayer A and the layer (A) was thus prepared.

In addition, the composition for light extraction layer preparation wasapplied to this layer (A) using a slit die coater and was heated anddried at 100° C. for 20 minutes to form a light extraction layer with anaverage film thickness of 8 μm. A laminate unit (Unit 1) including thebase layer A, the layer (A), and the light extraction layer was thusprepared.

Similarly, the color conversion composition for the layer (B)preparation was applied to the PET base layer side (the base layer Bside) of “Chemical Matte” 125PW (manufactured by Kimoto Co., Ltd.,thickness: 138 μm) as a light diffusion film including the base layer Band a light diffusion layer using a slit die coater and was heated anddried at 100° C. for 20 minutes to form the layer (B) with an averagefilm thickness of 13 μm. A laminate unit (Unit 2) including the lightdiffusion layer, the base layer B, and the layer (B) was thus prepared.

Next, the above two units (Unit 1 and Unit 2) were laminated by heatingso as to laminate the layer (B) and the light extraction layer directlyon each other. With this lamination, a color conversion sheet having astructure of “the base layer A/the layer (A)/the light extractionlayer/the layer (B)/the base layer B/the light diffusion layer” wasprepared.

Blue LED light with an emission peak wavelength of 447 nm was subjectedto color conversion using this color conversion sheet; an emissionspectrum similar to that in FIG. 10 was obtained, by which white lightwith XY color coordinates of (X,Y)=(0.25,0.22) was obtained. When onlythe emission region of green light was extracted, high color puritygreen emission with a peak wavelength of 530 nm and with a full width athalf maximum of an emission spectrum at the peak wavelength being 29 nmwas obtained. When only the emission region of red light was extracted,high color purity red emission with a peak wavelength of 630 nm and witha full width at half maximum of an emission spectrum at the peakwavelength being 49 nm was obtained. The coverage in the (u′,v′) colorspace with respect to the DCI-P3 color gamut standard was 98%. Therelative luminance of Example 11 with the luminance of the white lightafter color conversion in Example 10 as 100 was 104. An evaluationresult of Example 11 is listed in Table 4.

Example 10 was able to achieve both a wider color gamut and highluminance similarly to Example 1. In addition, Example 11, in which therefractive indices n_(A), n_(B), and n_(C) of the layer (A), the layer(B), and the light extraction layer, respectively, relative to lightwith a wavelength of 589.3 nm were designed to have a relation ofn_(A)≥n_(C)≥n_(B), was able to reduce light reflection on the boundarybetween the layer (A) and the light extraction layer and the boundarybetween the layer (B) and the light extraction layer and consequentlywas able to achieve improvement in the luminance of white light aftercolor conversion.

TABLE 4 Layer (A) Layer (B) Organic Organic Light Light-emitting BinderRefractive Light-emitting Binder Refractive Extraction Layer Material(a) Resin Index n_(A) Material (b) Resin Index n_(B) Resin Example 10G-2 Polyester 2.42 R-1 Acrylic 2.22 — Resin T12 (SP Resin T2 (SP Value =10.9) Value = 9.9) Example 11 G-2 Polyester 2.42 R-1 Acrylic 2.22Polyester Resin T12 (SP Resin T2 (SP Resin T13 (SP Value = 10.9) Value =9.9) Value = 10.6) Light Extraction Layer Peak Full Width at ColorRefractive Wavelength (nm) Half Maximum (nm) Coordinates Color GamutIndex n_(C) Green Red Green Red (X, Y) Coverage Example 10 — 530 630 2949 (0.25, 0.22) 98% A 100% Example 11 2.32 530 630 29 49 (0.25, 0.22)98% A 104%

INDUSTRIAL APPLICABILITY

As described above, the color conversion sheet, the light source unitincluding the same, the display, and the lighting apparatus according tothe present invention are useful for achieving both improvement in colorreproducibility and improvement in luminance, and are suitable for acolor conversion sheet, a light source unit including the same, adisplay, and a lighting apparatus that can achieve both high colorreproducibility and high luminance in particular.

REFERENCE SIGNS LIST

-   -   1, 1 a, 1 b, 1 c, 1 d Color conversion sheet    -   10 Base layer    -   11 Layer (A)    -   12 Layer (B)    -   13 Light extraction layer    -   14 Barrier layer

The invention claimed is:
 1. A color conversion sheet that convertsincident light into light with a wavelength longer than that of theincident light, the color conversion sheet comprising the followinglayer (A) and layer (B): the layer (A): a layer containing an organiclight-emitting material (a) that exhibits light emission with a peakwavelength observed in a region of 500 nm or more and 580 nm or less byusing excitation light in a wavelength range of 400 nm or more and 500nm or less, and a binder resin; and the layer (B): a layer containing anorganic light-emitting material (b) that exhibits light emission with apeak wavelength observed in a region of 580 nm or more and 750 nm orless by being excited by either or both of excitation light in awavelength range of 400 nm or more and 500 nm or less and light emissionfrom the organic light-emitting material (a), and a binder resin;wherein SP_(A)>SP_(B) where SP values as solubility parameters of thebinder resin contained in the layer (A) and the binder resin containedin the layer (B) are SP_(A) (cal/cm³)^(0.5) and SP_(B) (cal/cm³)^(0.5),respectively.
 2. The color conversion sheet according to claim 1,wherein the peak wavelength of the light emission of the organiclight-emitting material (a) is 500 nm or more and 550 nm or less, andthe peak wavelength of the light emission of the organic light-emittingmaterial (b) is 580 nm or more and 680 nm or less.
 3. The colorconversion sheet according to claim 1, wherein SP_(B)≤10.0 where an SPvalue as a solubility parameter of the binder resin contained in thelayer (B) is SP_(B) (cal/cm³)^(0.5).
 4. The color conversion sheetaccording to claim 3, wherein 9.0≤SP_(B)≤10.0 where an SP value as asolubility parameter of the binder resin contained in the layer (B) isSP_(B) (cal/cm³)^(0.5).
 5. The color conversion sheet according to claim1, wherein the binder resin contained in the layer (B) is an acrylicresin.
 6. The color conversion sheet according to claim 1, wherein thebinder resin contained in the layer (A) is a polyester resin.
 7. Thecolor conversion sheet according to claim 1, wherein a content w_(a) ofthe organic light-emitting material (a) in the layer (A) and a contentw_(b) of the organic light-emitting material (b) in the layer (B) have arelation of w_(a)≥w_(b).
 8. The color conversion sheet according toclaim 1, wherein at least one of the organic light-emitting material (a)and the organic light-emitting material (b) is a compound represented byGeneral Formula (1):

where X is C—R⁷ or N; R¹ to R⁹ are the same as or different from eachother and are selected from hydrogen, an alkyl group, a cycloalkylgroup, a heterocyclic group, an alkenyl group, a cycloalkenyl group, analkynyl group, a hydroxy group, a thiol group, an alkoxy group, analkylthio group, an aryl ether group, an aryl thioether group, an arylgroup, a heteroaryl group, halogen, a cyano group, an aldehyde group, acarbonyl group, a carboxy group, an oxycarbonyl group, a carbamoylgroup, an amino group, a nitro group, a silyl group, a siloxanyl group,a boryl group, a phosphine oxide group, and a condensed ring and analiphatic ring formed between adjacent substituents.
 9. The colorconversion sheet according to claim 8, wherein both the organiclight-emitting material (a) and the organic light-emitting material (b)are each a compound represented by General Formula (1).
 10. The colorconversion sheet according to claim 1, wherein the layer (A) furthercontains an organic light-emitting material (c) that exhibits lightemission with a peak wavelength observed in a region of 580 nm or moreand 750 nm or less by being excited by either or both of excitationlight in a wavelength range of 400 nm or more and 500 nm or less andlight emission from the organic light-emitting material (a).
 11. Thecolor conversion sheet according to claim 10, wherein a content w_(a) ofthe organic light-emitting material (a) in the layer (A) and a contentw_(c) of the organic light-emitting material (c) in the layer (A) have arelation of w_(a)≥w_(c).
 12. The color conversion sheet according toclaim 1, wherein the layer (B) further contains an organiclight-emitting material (d) that exhibits light emission with a peakwavelength observed in a region of 500 nm or more and 580 nm or less byusing excitation light in a wavelength range of 400 nm or more and 500nm or less.
 13. The color conversion sheet according to claim 8, whereinin General Formula (1), X is C—R⁷ and R⁷ is a group represented byGeneral Formula (2):

where r is selected from the group consisting of hydrogen, an alkylgroup, a cycloalkyl group, a heterocyclic group, an alkenyl group, acycloalkenyl group, an alkynyl group, a hydroxy group, a thiol group, analkoxy group, an alkylthio group, an aryl ether group, an aryl thioethergroup, an aryl group, a heteroaryl group, halogen, a cyano group, analdehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group,a carbamoyl group, an amino group, a nitro group, a silyl group, asiloxanyl group, a boryl group, and a phosphine oxide group; k is aninteger of 1 to 3; when k is 2 or more, r is optionally the same ordifferent from each other.
 14. The color conversion sheet according toclaim 8, wherein in General Formula (1), R¹, R³, R⁴, and R⁶ areoptionally the same as or different from each other and are each asubstituted or unsubstituted phenyl groups.
 15. The color conversionsheet according to claim 8, wherein in General Formula (1), R¹, R³, R⁴,and R⁶ are optionally the same as or different from each other and areeach a substituted or unsubstituted alkyl groups.
 16. A light sourceunit, comprising: a light source; and the color conversion sheetaccording to claim
 1. 17. The light source unit according to claim 16,wherein an arrangement of the light source and the following layer (A)and layer (B) included in the color conversion sheet is an arrangementof the light source, the layer (A), and the layer (B) in this order: thelayer (A): a layer containing the organic light-emitting material (a)that exhibits light emission with a peak wavelength observed in a regionof 500 nm or more and 580 nm or less by using excitation light in awavelength range of 400 nm or more and 500 nm or less, and a binderresin; and the layer (B): a layer containing the organic light-emittingmaterial (b) that exhibits light emission with a peak wavelengthobserved in a region of 580 nm or more and 750 nm or less by beingexcited by either or both of excitation light in a wavelength range of400 nm or more and 500 nm or less and light emission from the organiclight-emitting material (a), and a binder resin.
 18. A displaycomprising the light source unit according to claim
 16. 19. The displayaccording to claim 18, having a color gamut coverage of 96% or more inthe (u′,v′) color space with respect to the DCI-P3 color gamut standard.20. A lighting apparatus comprising the light source unit according toclaim 16.